Save yourself some money and buy the Casio PX 560. No iPad or apps needed because everything is onboard as it should. Great allrounder with everything you need.
So many great choices when it comes to 88 keys, but I, too, think the PX560 is among the better choices in many respects. I used to own a Casio PX330. An excellent action (as subjective as it can be, it is a very solid keyboard action) and great piano sounds at only 24 pounds. The Yamaha P515 looks promising, but at 48 pounds, I won't consider it as a gig instrument. The PX560 is 26 pounds. Just recently I purchased a Numa Stage (28 lbs) by StudioLogic. I should have purchased the PX560.
Anyway, any 88 key controller paired with either vArranger or the SD40 would make a great 88 key arranger.
The P515 has wooden keys.. which makes it heavy...
I don’t think either the p515 as well as the fp90 are meant for gigging..
I allways asumed them being aimed at home players and kids starting piano..
If you need to move it a lot, and buy it for the typical keyboard sounds, the px 560 might actually be the best choice.. despite having a less authentic action, and not having the best arranger styles.. it still is a good instrument, just not the best, but does have its adavntages..
However if only weight counts... you could also look at a nord stage, its in the same weight category... and asuming you will use it with an sd40, would also make a very very nice setup..
There is so many options...
thats what makes choosing hard..