When I visited my parents (they live in East Frisia near the town of Norden) some weeks ago  I bought an eight-stringed  frisian hummel from fellow FOTMD member Wilfried Ulrich. He is an outstanding artisan and showed me also his other instruments (including several hummels, epinettes, monochords, dulcimers and bowed dulcimers (one even with sympathetic strings!). If you ever visit Northern Germany try to arrange a visit and shopping at his place, you will not be disappointed:
http://www.ulrich-instrumente.de/

I also purchased Wilfrieds book about the history of the hummel, his instruction book and several collections of hummel tabulature. According to him the tabs should also work on a dulcimer.

Since then I try to play the hummel. It's big fun but also quite challenging in it's own. 
The fretboard is much wider than on my dulcimer and covers four strings. So I could even use it for learning dulcimer chord playing.  That's the nice part. 
Wilfried recommends in his instruction book to learn a kind of fingerdancing style. The benefit is, of course, that you can play notes on the other strings. I will need some time for it though since I play my MD only with the noter. So finger dancing  is a challenge, but a welcome one!
The other challenge  is to get the right strumming pattern to play all strings (including the four drones without fret board) without sounding bad or eleminating the melody strings. On my dulcimer I use the thumb for strumming from the melody strings to the drones and the HEDIM pick for playing from the drones to the melody strings. On the hummel you start always with the melody strings  and play the drones just when they fit in (usually at the beginning of a bar). So this is a change as well.