Maybe "ok" for a little home use, but no for operational use in an arcade for 8+ hours a day, the 3.3v and 5v are far too regulated, and heck I'd be surprised if its even 4.8v when it hits the board, plus if your powering MPEG, Drive board etc, then it's probably close to pushing the limits, modern ATX are more for higher amps on the 12V, something arcade boards don't use - 12V is generally for cooling fans.
You need a decent PSU with adjustable 3.3v and 5v to get the exact sweet spot, Naomi PSUs with adapter wiring are perfect, ATX they've never been stable.
But each to there own, I am only going by my experience - and the fact I've had 1000s of people email in the past saying why there Daytona 2 or Rally 2 constantly freeze.