Welcome to the forums, AudioGeek.
I've got an fp-7 myself. I don't do any mixing/sequencing or anything though so I can't help in that department. the FP-7 only has two tracks you can record to. (Without resorting to doing the mixing on computer software, I suppose.)
Always remember that a digital piano does make noise when you're practicing with headphones. The standard key thumping. It might bother some in the room, but at least your neighbors won't care. I don't hear the keys at all when I'm playing.
I never looked at the higher end stage pianos due to budget considerations so I cannot comment on those. The one thing I do like about the piano is decent connectivity. Audio In/Out, Headphones(x2), usb (for midi), midi in/out, usb thumb drive and support for 3 pedals with half pedal support.
The thumb drive on the fp-7 can be used for the audio key feature (I've not used it for that), just to store my recorded songs on. It's an easy way to transfer performances over to the computer for backup.
I figured that even If I got tired of the built in sounds I could eventually upgrade to a computer based sample or software piano. With the audio outs I could always hook up external speakers if needed. I was pretty much looking for something with enough features that I could live with it for a while. It's working fine so far.
About the only downside is the built in music rest where the darn thing is too short to hold up normal sheets of paper without them flopping over and falling down after some time. Be sure to have something like card stock or cardboard behind to add some support. I was honestly thinking of buying a sheet of plastic and rebuilding the stupid thing at some point.
The rest is 7.5" tall, leaving a good 3.5" of paper unsupported. Even one of my thick spiral bound lesson books likes to flop backwards.
Overall, I'm fairly happy with the purchase I made. I know some people that like the keyboard action of the fp-4 better but I went with what I could try personally.