Confusion is beginning to creep in here. Lets clarify things...
The EXP is less expensive but it is also one piece so you lose the modular options (tech plate versus Nomad plate, etc) so I'd skip it and go with the Nomad XT.
The XT starts as a standard Transpac harness and adds the wing and buttplate, so discussing the pros and cons of Transpac versus Nomad is a little pointless.
If you already have a Transpac, then just get the butt plate and the Nomad wing. If not, just get the Nomad XT as it is probably cheaper that way.
Personally, I did not like the bulk of the shoulder pads and back pad on the Nomad so I removed them. It makes it a lot cleaner and less bulky.