Don't own an hx2755, but I was just playing Sonic the Hedgehog 3 on my H4355 with MorphGear last night.

I had about 16MB of ram free for program usage, but running the game with any kind of sound (high, med, and low) slowed it down a bit. With low quality sound, it wasn't bad, and the sound was actually better since it was less choppy, but it still wasn't ideal.
With the sound off, it's a ton of fun, but I miss all the little noises sometimes. I always have to click the boxes for both "enable sound" and "emulate" in the sound section to hear anything. Kinda curious what enable sound is supposed to do with emulate turned off.