Popping in briefly to +1 what John says really. Pretty sure David isn't on here but I really should check in more often, since the Degsy reposts reminded me this forum existed. Catch up time, I think...
As one of the MAMEr people, I'd be the first to admit we need to elevate a few more things to do with art etc to get to the same standard as MFME was, but if there are any obvious art type things that are just unimplementable for a working tech, let me know - there are tricks with SVG images and other scripting that can be used as workarounds if need be.
My dev time is nowhere near as big as it was in the AGEMAME days, but if I can do a bit, I'll try to.