They look like fun -- and really portable! Although I confess that when I tried to play a similar instrument I got totally muddled. I play regular Appalachian dulcimer on my lap with my thumb and forefinger leading up the fretboard. When I tried playing a strumstick, which is held guitar style, with my pinky leading up the fretboard my synapses fried -- despite the fact that I also play guitar, and have no trouble switching between it and my dulcimer. I think it was the meating in the middle that caused the confusion. It's all what you're used too.
As for the problems mentioned with dulcimers...they're generally solveable. I use a strap that goes behind my back to secure the dulcimer when I'm playing hard or on a chair that is too high. Ron Ewing makes excellent dulcimer capos out of wood that are widely available. And as for volume, I can crank my McSpadden up and drown out my husband and his sister on mando and fiddle. A number of players put their dulcimers on edge on their laps, rather than flat, either with or without straps. Its a style that seems to have originated on the west coast of the USA, and it does solve the slipping and projection problems. Steve Seifert does amazing things playing that way although I've never gotten the hang of it myself (it seems to work better with teardrop rather than hourglass dulcimers). Check out his website at Stephen Seifert's website
But in the end, anything that advances the dulcimer is a GOOD THING! So go for it!