To me, an MVS converter defeats the whole point of the novelty of owning an AES. Imagine a PC Engine with a Sega clamshell sized combo sticking out the front.
If you want a functional system and more and cheaper games, a CMVS is the only way to go. Even the best AES models for either RGB or composite aren't as good as a well-made CMVS and unibios is a must have.
If you've never owned an AES console, you'lly be shocked by how cheap and flimsy it feels. If you really want one to look at, your best bet is to buy a broken one for cheap and get a CMVS for actually playing games.