From reading other postings, it appears the JTAGICE MKII is not just an upgrade of the original JTAGICE with debugWIRE added. The new MKII appears to be missing some functionality and some processor chips in its support list. ATMEL did say the MKII AT90CAN128 support will be added to in the next AVR Studio software release, but the MKII still seems to be missing some other stuff.
It would be nice to have debugWIRE for future projects, but I want maximum functionality for the ATMEGA128 soon and AT90CAN128 later, even if I have to skip having debugWIRE. Does anyone think the MKII will completely catch up with original sometime in the future or should I just get the original JTAGICE and forget the MKII?