I picked up a Guens double-reeded student (china) model and have been playing it for a half year or so. It is my first squeezebox, so I don't have much to compare it to, but I have been very very happy with it so far.
I have managed to get used to the angle of the keys. You can use your thumbs, although it's not ideal. As I advance I find myself using my thumbs less and less; if you're fast enough you can still kinda play smoothly even without using the thumb to cross under.
The action is indeed heavier and noisier than I would like. I figure there ought to be a way to stuff some cotton between the metal rods and the wood block under the keys they slide in, but I haven't experimented yet.
I would love to upgrade to a better instrument one day, but if I pay 10X what I paid for this box, I would want the action to work better, and I get the impression the pro geuns models have the same type of action as the China-made ones.
I ~think it should be a smoothish transition from a guens hybrid to a peguri ( or a praktikal, though they're probably harder to find than meteors). Comments on that from someone who has played both would be welcome, especially for the left hand.
Though it has accordion reeds, it sounds much closer to me to a bandoneon than to any of the accordions I have heard. You can't play a melody on top of a chord with good balance, but I understand this is just how things are with a bandoneon; you can play up to two melodies or you can play chords, but not at the same time. I could have deduced that from how it works, but it was still a slight dissapointment coming from a piano background.
I imagine it is much less stable than a "real" bandoneon; that is the cost of having more freedom for your hands to move. I only play sitting, and with each side on it's own knee for support.
The bellows are shorter than on an expensive bando, but since it's unisonoric I don't think that's as much of a big deal.
Minor maintenance issues:
1. When I first got it, some of the rods rubbed against each other slightly, not a big deal but enough for me to notice. It was easy to gently nudge them away from each other to eliminate that source of noise.
2. The screws for the straps pulled out of the wood blocks (I suspect the screws are going into end grain; hard to say cause it's covered in celluloid), but I just solved that with some glue, and they haven't come out since then, though I'm careful not to lift the instrument by the straps alone. I figured the glue was less invasive than drilling out larger holes and using larger screws; I'm pretty sure I can still break the screws free and do that at a later date if I have to.
3. The key tops on the air valves can come unscrewed easily during handling; thank god the actually keys don't have this problem!
Again though, this is a great instrument for the money!