I have a nearly identical system to @k4lmp above. I added the 68010 first (only cost about $5 but took a month to arrive from China), think SysInfo reported about a 10% speed improvement off that. I then added 4MB through a GVP sidecar (also did the mod so it receives power directly through the side expansion slot), SysInfo reported about a 35% improvement with that, so all-in-all I'm rocking a 145% over stock speed system, tossed in an Indivision ECS, chip ram mod and a rom switcher and wahoo, retro gaming fun! ;-)
Definitely recommend the 68010 for the price though, just wish there were more options for an A500 that didn't cost an arm-and-a-leg! :-/
