Flash Hiders says it uses it in the back of the manual even though it doesn't have the Arcade Card icon on the front. Someone stated that there were a few sound effects that wouldn't be heard otherwise.
Flash Hiders, I didn't notice any difference in sound effects (back in the day) but I do know it loads all the character graphics initially if you use the Arcade Card, and thus will have no load times between matches which is really nice!
Also, I've noticed that memory in the Arcade Card (Pro, at least) will retain the data held in it for some games even through a system reset. For instance Mad Stalker and its crazy long initial load, will go super fast if you just did a soft reset. Speaking of which, Mad Stalker is pretty good and underrated.
By the way this is the most awesome and true statement I agree with all year so far:
Sapphire may not be the greatest shooter ever. But I find it to be a total celebration of the PCE. The colors, the style, the music. It's all just comes togeather so well and screams ''THIS IS PCE, IN YOUR FACE BITCHES!!''.
Most systems tend to have slow drawn out deaths, the last few years having nothing but awful cheaply made shovelware. Street Fighter 2 Alpha on SNES? ROLF.
Now the PCE however, went out on SAPPHIRE. It didn't sit around on life support, it held a massive fireworks show and went out in full glory from the people that gave it birth.
If I were a console and had to die, Sapphire is how I would die...! Though to be historically accurate it kind of went out with Dead of the Brain, which I haven't got around to playing yet. Has it been language patched yet I wonder..?