cymbalom sighting
His instrument was a little bigger than my dulcimer (definitely thicker) and about three and a half octaves (fully chromatic); they come bigger. (I've seen pictures of ones that are about five octaves, but like pianos and concert harps, they're not so mobile.) The layout seems to be similar to that of a hammer dulcimer; his demo was pretty fast so it was hard for me to spot everything. Even though his treble bridge was farther from center than I expected (it sure didn't look like 3:2 to me), he demonstrated that the center bridge is tuned in fifths. He had four strings per course rather than the dulcimer's traditional two, which makes for a richer sound and a bigger tuning hassle. (His lowest notes had three strings per course, because the heavy wound strings would be overwhelming with four.)
His instrument had dampers, and he implied that this is pretty common. Dampers on hammer dulcimers are very rare (I'm trying to remember if I've seen anyone other than John McCutcheon use them), but they would be useful at times. He also played sometimes with heavily-padded hammers.
The thing I found most interesting about his demo was his approach to scales. When I think about the hammer dulcimer, and especially when I'm explaining it to others, it's all about the series of diatonic scales. Play here for a D scale; now see that G that was the fourth of that scale? Start there and play the same pattern for a G scale. See the C in that scale? And so on. I point out that the accidentals that you are most likely to need (such as the sharped sevenths) are conveniently to hand, and that nothing is all that far away.
He did nothing of the sort. He demonstrated the range and layout by rapidly playing a three-octave chromatic scale for me. (This is why it was hard for me to deduce all of the layout; he was jumping around for all those accidentals.) This seemed utterly and completely natural to him. I could play a three-octave chromatic scale on my dulcimer, but it certainly would not flow naturally. On the other hand, when I asked him initially if it was laid out in diatonic scales like the hammer dulcimer, he didn't seem to get what I was asking. And no, I don't think it's because he didn't know the word "diatonic"; I think it's just a very different perspective.
Now granted, the way you think about music is heavily influenced by the types of music you play. I play a lot of renaissance music, some medieval, and little that is more modern. I don't know what he plays when he's not playing folksy Jewish music for services. He could be a classical musician for all I know, where the points of reference are probably very different. He treated his cymbalom as one might treat a piano; I treat my hammer dulcimer as one might treat, I don't know, maybe a pennywhistle (well, except for that play-one-note-at-a-time thing). I found it interesting.

Tangentially -- Dampers
Now to go back and reread the rest of your description again, since I've been curious about the differences for a while...
no subject
I couldn't play the thing worth a damn -- playing Renaissance dance music on the chromatic instrument is *much* harder than on a diatonic, I found, because of all the jumping around you have to do. So I traded it to him for his old big dulcimer. Not as pretty, either a sight or a sound, and weighs as much as a piano soundboard (well, no, but it *is* very heavy), but easier to play, sturdy as a rock, and can be heard clear across a large field...