Congrats on the beautiful guitar- I picked up the exact model and color new from Rich around a year ago, and you will love it. I also like the fact that it's a somewhat controversial guitar in the "Z" model. It polarizes people to either love it or hate it.
I've used the bridge with the ZPS bar both in and out and like it both ways. I actually prefer the more firm feel with the ZPS bar in as it's easy to accidentally push on the bridge with it set to fully floating. Plus when you do big bends with the bridge fully floating you pull the surrounding notes quite flat during the bend. With the ZPS bar in I haven't had the problem with the bridge returning flat after pulls ups but I don't get too crazy with them. I'm more used to a blocked trem like on a Wolfgang anyway. I haven't found it necessary to replace the pickups either. They might not sound very articulate through certain rigs (based on other comments), but through my Marshall DSL100 tube half stack they sound fantastic even without using my pedal board. Positions 2 and 4 on the switch have that great "quacky Strat" sound to them when you want to change things up a bit.
And that neck, oh that neck... it's like greased lightning to play. I have a couple of other guitars, including Les Pauls with baseball bat thickness necks. They all have their place in the arsenal, but the RG2550 neck is like a satiny smooth dream to play.
