Hmm, what exactly is the 'more cores' option? If it's more games, i'm always all the way for that and bug fixs.
And i also like very much the gui as it is now. The xbmc one personally, i think it clashes and don't fit well with the CoinOPS design.
The only thing i could change on the gui side, besides that manufacturer thing for later maybe, is the opacity on that section of the info. Instead of being total black, make it a little softer and a little transparent. That way it doesn't block the videos or screenshots on the lower right on the frontend.