Ken, I'm not ready now to get a new dulcimer with the flexi-frets, but I would like to someday.  I did play one once, though.  I think you are probably right that inserting and removing the frets is not so easy that you'd be putting them in and taking them off in the middle of a jam session.  But it's not that hard either, at least not with the little tool Dwain supplies. I was surprised that the slots were not really noticeable by feel when the frets were not there.  But I only play with my fingers. I wonder if the "empty" slots would affect a noter sliding up and down.  Maybe we can have @elvensong answer these questions when he gets his.

Dusty -- I'll be interested to hear your take on the flexi-frets.  I've heard from others that removing/replacing frets is not as easy/simple as it is made to sound.

Lucky you! That'll be quite an instrument.

Dwain is building a Concert Grand for me with flexi-frets. Brilliant idea! Opens up the entire dulcimer fret possibilities on one instrument. I'm hoping to have mine in time for Walnut Valley. 

I'm joining this conversation late, but I do have one suggestion: flexifrets . Flexifrets are frets that can be inserted and taken out by the player.  I might not want to buy a dulcimer with a 4+ fret, but if it were a flexifret, I might be curious. I would still, however, want a 1+, so if you install a flexifret for the 4+, you should also do it for the 1+

Incidentally, Paul Furnas only plays Renaissance and early music, and he claims that even in DAd, a 4+ would be more useful for him than a 1+ or even a 6+.  He brought a diatonic dulcimer to a luthier to add the 4+ fret, but the luthier assumed he misspoke and put on a 6+ instead! (Paul ended up selling that dulcimer.)

Anyway, I've been thinking about getting a dulcimer with a true diatonic fretboard but then adding a flexifret for every half fret, so the dulcimer could function as truly diatonic, fully chromatic, or anything in between.

Lisa and Strumalia, Thank you for you responses. This site has lots of good info from people in the trenches. I am thinking of the 1+ and 8+ now considering that I might start experimenting with the mixo. tunings.

Oops, I answered off the top of my head.  It's true the 4+ is relatively the same fret as the 1+ for your tuning.  But I forgot about how the rest of the scale maps out.  Today I got out a dulcimer and studied the modal charts here .  Assuming my poor muddled brain has it right this time, if you want to play a Dorian scale starting at the 3rd fret you will need both a 4+ fret and an 8+ fret.   

Many tunes don't use the 7th note of the scale, and it's pretty easy to bend a note in the middle of the fretboard, so you could play a lot of Dorian tunes without the 8+ fret.  Still, the 4+ fret is not as magical for CGG tuning as the 1+ is for CGC.  I see several paths forward depending on where you want to go: 

1) You could order a dulcimer with 1+, 4+ and 8+ frets (6+ optional).  This dulcimer would be specialized for Ionian 1-5-5 tunings like CGG.  You might never be able to re-sell it, but it would be quite the conversation piece. 

2) You could get a dulcimer with 1+, 6+ and 8+ frets, which is not uncommon.  Play it in CGG and see what happens.  You'd always have the option to re-tune CGC.  It's not your favorite tuning, but CGC would give you Ionian (with 6+ fret), Mixolydian (no extra frets) and Dorian (with 1+ fret) ready to go.  Not Aeolian though: for that you'd also need... here it comes... the 4+ fret!

3) Get a chromatic fretboard.  Beyond a certain point it is easier to have all the frets and be done with it. 

4) Give up on extra frets and re-tune for Dorian mode (CGF). 

5) Experiment and see which extra frets work for you.  Straighten out a paper clip and use masking tape to hold it in place where the extra fret should be.  A total kludge, but it can be fun. 

I play using 2) and 3) and 4) above on different dulcimers, in different playing styles, as the mood strikes.

Lisa G. brings up a very good point- a dulcimer with added 4.5 and 11.5 frets would be quite difficult to sell.  Most folks who use extra frets in addition to the common 6.5 fret would want either 1.5 and 8.5 or all the way to chromatic.

FWIW, I play only in noter style and 'usually' in DAA type tuning, but I have found it very useful in oldtime fiddle sessions to have the two extra pairs of frets;  6.5 & 13.5, and also 1.5 & 8.5.  But for relaxed playing at home I do also enjoy and can appreciate a total diatonic fretboard and retuning to different modes while playing older traditional music.

As long as there are still a few diatonic fret spacings I've not found it hard to keep my bearings visually.  Once you get to chromatic I'd recommend having a few inlaid fret markers (like guitars and fretted banjos tend to use).

Matt, Thank you, I will look for the Daa forum.

Ken, Thank you too. I am not sure of the style I play. I like to play my melody on the middle string while strumming instead of the normal melody string. I use chords on two or three pieces but usually let the melody strings drone on.

Lisa, thank you. I was wondering about the fret issue and will have to think about the 4+ and 11+ or the 1+ and 8+ situation. Which gives you the dorian?

Short answer: The equivalent frets for CGG tuning would be 4+ and 11+.  However, depending on the scales and chords you want to play, you might prefer 1+ and 8+ anyway.

Long answer:  For people who play in DAD/CGC tuning, the scale starts at the open 0 fret.  Adding the 1+ fret gives them a flatted 3rd note.  That note is critical for playing minor scales and very handy if you are lazy like me and you don't want to re-tune or capo every time you want to play the blues.

In DAA/CGG tuning, your scale starts at the 3rd fret.  The 1+ and 8+ frets give you flatted 7th notes.  This lets you play a Mixolydian scale without re-tuning.  If you wanted a flatted 3rd note instead, you'd need the 4+ fret.

So... do you want to add a flat 3rd or a flat 7th?  Would you rather play Dorian and blues -- or Old Joe Clark?  The easier question is how often do you wish you had a fret at 8+?  Compared to how often you wish you had a fret at 4+?  If you've never wished you had either, maybe you don't need extra frets.  How often do you re-tune now, and why?

That was all about scales.  I can't help much with chords in CGG but you get these additional notes for building chords:

E-flat and B-flat with a 1+ fret

A-flat and E-flat with a 4+ fret

Another factor to consider is the 1+ and 8+ frets are fairly common now.  You can find tab and chord charts (though mostly in DAd) and it won't be hard to re-sell a dulcimer with those frets.  The 4+ fret is less common and it will be harder to find resources and harder to re-sell.

What Matt said -- you will get a few extra notes, but it depends on what kind of music you're playing whether those particular notes will do you any good.  In your current repertoire, are the significant (say even 10%) songs that require those 'non-traditional' notes??  

Are you playing Fingerdance or Chord Melody style?

The DAa forum would give you more guidance.  In DAd, the 1 1/2 - 8 1/2 frets give you the ability to play F on the D strings and C on the A string.  You would gain the same notes DAa or DAd.  Whether you would use them depends on the songs you play. 

I have been thinking of a second dulcimer with extra frets at the 1 1/2 and 8 1/2. But I like to use the DAA tuning down a step for singing. I know that DAD players gain some tunes/songs with the extra frets but I am not sure if the 1 1/2 and 8 1/2 frets would be the correct extra frets for a DAA (CGG) tuning system. Any advice? Thank you!