I guess my take is that I don't WANT to have to use two keyboards, one for arranger, one for piano. Why not simply combine the two, and save yourself a fortune!
If all you are is a pianist, well, that's all you need. But a true 'keyboard player' needs to do it ALL... whatever they want, whenever they want, with as little compromise as possible.
I admit that, simply as a sound source and as a pure arranger, the T3 has a lot going for it. I might even get one if it had a 76. But when my clients, or the band I am in need a full(ish!) piano part, I can't exactly say 'sorry guys, this thing isn't big enough!'.
Conversely, If they need tracks or automatic backing, I can't turn round and say 'sorry, this is just a piano, it won't do drums and bass!'
Perhaps not owning or working at a music store makes me a bit more penny-conscious than some around here, but cartage is getting more expensive, gigs are getting rarer, and anything that interferes with my versatility has got to GO...