I'm assuming you meant GroovyMAME, for windows, and not the Linux-based GroovyArcade? Linus has aother ways to manipulate modelines, you can get away with many different video cards, though there may be other concerns.
Atom-15 is probably a good idea for a cab, or some other form of boot protection, though it ultimately depends on the monitor. A decased TV/chassis combo from the 90's owards is probably fine, the rolling way it tracks sync is pretty forgiving. But an older arcade monitor might be pretty sensitive, and you're best off protecting it. Something like a universal chassis from aliepxress or whatever i really don't know about.
There isn't much of a list for ATOM-15, just people reporting problems occasionally on there forums. Search for Atom-15, Atom15, Atom 15, etc. and then try finding your proposed card. It looks like newer cards like the R9 370 and 380 have issues, and stuff like the 7870's don't, and in between is in between.