Mustang pro is pretty solid already and it doesn't look like the LE/Premium will change game play much. The pro has full LED lighting, rather evolved rules already, not buggy. It doesn't feel stripped down or lacking to me.

The flyer I have says 4 songs for the pro. That's what's on mine. Pretty innovative rules around the gear shift multiball where the player can take a 3-ball multiball, or choose to go for a 4, 5, or 6 ball multiball with higher super jackpots (and higher risk of not starting it before draining the last ball).

Every time you complete the GEARS drop targets, you go up a gear. Once you're to gear 3 (3 completions of the bank), "start multiball" lights on the scoop. You can avoid the scoop, or even abort multiball if you do go in. It says "Staring multiball in 3.......2.......1" with the text "hit flippers twice to abort". So you can manually abort and go to a higher gear with more target bank completions, up to a 6-ball multiball. Pretty cool.