I'm pretty sure they're not worth even trying, because A: the pushing part of the button is flat, and B: it's too small. I'm not 100% positive, but I'm almost positive I was on a cabinet that had like 2 out of 6 of those in it, it was like MvC2 or something, and they felt like absolute crap. If you want the easiest feel go with Competition pushbuttons, and if you want the most arcade realistic feel go with horizontal pushbuttons. Best to stick with what you know when it comes to things like joysticks and pushbuttons.
-Good Luck
-CthulhuLuke