Chestnut as Tonewood: Can you only tell by the holes?!

What is this 1981 Leonard Glenn top and back made from, all you builders out there? Looks as though it should be chestnut, but it's got no holes.

...Unlike this later 1983 Clifford Glenn

...or this earlier 1964 Presnell. Similar pronounced grain and light gold colour, but slightly whiter overall.

We use chestnut as a workhorse wood for fences or cladding. Why then is it not just serviceable but also desirable as a tonewood for many famous dulcimer makers - Sam Carrell liked it best of all, the Glenns thought it made "one of the nicest sounding instruments they'd ever created", Keith Young, Mize etc etc. Does it only work with some designs, is it best as a top, only when very thin? Is it difficult to work, or is it simply used rarely because of limited availability?