For what it's worth, I played through all the 8 bit platformers in Sonic Mega Collection Plus (PS2 edition) and Sonic Gems Collection (GCN) and enjoyed myself and didn't see anything that struck me as obviously wrong with their Game Gear emulator.
Sonic 1 and Sonic Chaos on the PS2 and Sonic 2 and Triple Trouble on the GameCube all seemed just fine to me, although someone with more familiarity with the source material perhaps might notice issues.
It was actually my first time playing them and the experience definitely wasn't awful like if someone inexperienced with Sonic 2 for the Genesis had tried to play it on Sega Smash Pack for the Dreamcast with its awful audio emulation.
That was so bad that I don't think you would've had to have ever played Sonic 2 to know that it wasn't correctly represented on that compilation...