My A500+ was ace. I never had incompatibility issues - then again, I always read the back of software boxes under the section "Hardware Specifications Required".
Many a day I had fun playing "Bart Simpson Vs The Space Mutants", one of the Dizzy adventures or another, the F/A-18 Flight Simulator. I'm only 20 now, so you can imagine how young I was at the time.
Don't mess with the A500+.
I agree about the A600 tho. It felt too small - keys were too close together, no num pad. My friends didn't do anything with their A600s that my A500+ couldnt do.
How I miss those days.
Samuar