Yamaha DTXpress/DTXplorer/DTXtreme

This is really embarassing. I just won a used DTXPRESS kit for $585 on
ebay, shiping is an extra $90. But I thought that I was bidding on a
DTXPRESS III.

This kit is for my two sons, who are novice but serious drummers, to
use in church. Is a DTXPRESS worth that much? Used DTXPRESS III's
usually sell for around $750 on ebay, and shipping is around $50.

Did I screw up badly? What does the DTXPRESS III have that will be
missing from my kit. Will the pads be ok? single or double trigger?

I couldn't find any specs on yamaha's websites for the older kit.