Well I ended up buying this Shuttle and here she is!
It actually looks a lot cooler in person than I thought (never thought they looked that great),
but it's definitely big! Dwarfs the CoreGrafx.
The controller is comfy but I'm not sure if I like it any more than the regular pad.
Maybe I'm just used to the regular one?
Unfortunately the system has one problem though.
I posted this in the repair forum, but I think the soldering on the control port has become loose.
When I start up a game most of the time the Run button and left on the d-pad are unresponsive.
But if I jiggle the controller input to the left it seems to connect and I can play games perfectly.
I've tested this with a couple controllers and the result is the same.
I think the guy who sold it to me knew the problem as he posted "tested until the title screen only" and accepts no returns of course. Plus the guy was being really rude and short with me while I was messaging him to arrange payment and whatnot, which is extremely rare with Japanese sellers. I had a seller today who told me I should take care not to catch a cold with this sudden turn in the weather! Oh well, you're bound to run into some shady sellers from time to time.
Anyway, this doesn't seem to be too big of a problem, as on the repair forum someone said you could just reheat the soldering contacts of the controller unit as they sometimes get loose with time or rough handling.
Has anyone had any experience fixing these kind of problems? I've soldered things before wiring up custom controllers and whatnot but I also don't want to totally ruin this system if it's tricky.