I was trying to work with someone at sweetwater but they don't know what works in biab. They sold me a piano one that wouldn't work.
What piano VSTi did you get? It will probably work ok once the midi channels are correctly assigned.
If you want a reasonable general midi sound set, have a look at
Coyote Forte.
There are demos at the above link so you can hear how it sounds.
Regards,
Noel