well, ssf auto-recognized (?) the aspect ratio and adjust accordingly. From my initial testing, nights and xmas night, along with high velocity boot the bios in 4:3, and then the screen expands to 16:9 automatically from the sega logo on.
but.. this requires booting up and starting all 247 games. From my initial results this morning running through the first 50 games, here's what i've come up with:
Batman Forever - The Arcade Game (? - error is in wide screen)
Battle Arena Toshinden Remix
Battle Arena Toshinden URA
Burning Rangers
Clockwork Knight
Clockwork Knight 2
Command & Conquer
Croc - Legend of the Gobbos (? - widescreen, but can't go in-game)
also it would be helpful for others to try on actual hardware. in emulation, if i start the widescreen game, and tick "enforce ascept ratio" it goes back to 4:3, but i dont know if that's the games normal resolution or if it's enforcing my monitor's 4:3 resolution.
Anywho, someone check them out and let me know 🙂 i;'ll keep testing away