One big thing to consider is if he will want to take it places
The keyboard player in the trio I play in has tried just about every keyboard/controller there is.
Just remember that with midi,you are never stuck with the internal sounds.
Back to the keyboard player,with all the boards he has tried,he tells me to this day,there is nothing that has the action like a real piano like the "OLD" Roland RD series keyboards.The only reason he stopped using his was because of the weight.Keep in mind,if you want it to play like a piano,it will be heavy.All the new "weighted key" boards that are light play better than a non weighted board,but do not play like a real piano
Oh and by the way,he still uses his RD-300 at home where he doesn't have to move it