Hi,
I confirm that Caanoo is really perfect to emulate almost 80% of the MVS portfolio, in virtue of the 4:3 low resolution screen. Anyway, you need the roms to be dumped exactly. I think I am not allowed to post the link, but make it in google "gngeo caanoo romset" and you will find it.
More, I think it is cheaper find a used caanoo on ebay than buying a new Neo Geo X. Still Neo Geo X is limited to few games for now.