Mixcraft7 has some nice sounding ensembles and kits and you can run Pianoteq inside it. You can assign sections of your keyboard to layer or isolate the types of instrumentation, to include Pianoteq. Really it's like expanding Pianoteq and adding 900 and some odd types of instruments and packs to it. plus it's a recording studio software. When you get everything all channeled the way you want it you can save that under what ever file name you pick. I run Mixcraft through a Korg NanoKontrol2 Slim controller to get real sliders for volume and to control turning on and off of the tracks of instruments I set up. I do that through midi mapping, which in no way is difficult just a bit tedious. There are controllers you can get that will use a midi learn function and do it automatically but they cost more than I wanted to experiment with, I think this was $59 US. Now that I've experimented though I may move up in the future to one of the $300 units that appear in Mixcrafts drop down.. I think a Mackie Mini is one for example.
Pianoteq expression is awesome, I agree. And latency is not even noticeable. Most of my grand pianos in Pianoteq exhibit more dynamic range easier to control than my real grand. Course the resonance on my real grand is real, Pianoteq is very good at that but not that good. While I have a very decent sound system, the DJ at a wedding my music played in proved to me there are better out there !