Thanks DrDan... anyone else with experience or insight into these composition/production tools?
I will embellish a little on Dan's response:
1-Toontracks also make EZMix: a mix and mastering program
2-Each Toontrack product has additional add-ons that you can purchase, as Dan indicate it can get expensive.
3-EZKeys2 is not just dedicated to piano or keyboards. One can apply an EZKey2 track to any sound. I have used piano tracks from EZKeys2 and used a full string orchestra as my sound source. I also have imported MIDI string grooves into the user option of EZKeys2. You can combine them with EZKeys 2 groves to power a Kontakt string section, or any other section; I have used brass sound sources also.
As Dan said it is all MIDI so you can edit those tracks to your hearts content.
I like to take the Utility track from BiaB, bring it into EZKeys2, then use EXKeys2 grooves to change said track. Then I bring that modified track back into BiaB. There are a number of options when using both programs together.
As suggested look at the videos to get a better view of what Toontrack packages can do. I should say that I have EZKeys2 and EZMix only, thus I can not comment on the other available software.
I hope this helps.