I would suggest looking at the DTX502 Series kits since it features the new DTX502 module. This module contains may new sounds, groove tools, expandability and you can import you own samples into the module. There are three versions of the kits: DTX522K, DTX532K, and DTX562K.
Here is the link to the product page for more details.
Let me know if you have any questions.
DTX Product Specialist