Yes very BIG difference.(especially if you play styles, not SMF only).
As an old PA50 user I can tell you this.


PA 500 - advantages
more poly/more RAM/
newer sound generation (EDS)/RX (acoustic GTR trio styles competes with MEGA voice styles from yammy)
multi pads will play loops like Yamaha (pa 80/60/50 and micro can't)
more fills,more intro/endings
old styles retweaked for the better/less fill issues,
more style areas compared to PA 50/micro,
will still load pa 80/50/micro style files .
Guitar mode
Song Book ( great feature)
3 Ibs lighter and also less bulky (compared to 50)


Micro wins for size/portability/great 2nd board
PA 50 shows it's age/price/advantage compared to S710.But Pa500 and S710, (good competition)