making wiring harness from scratch

My oldest installations of the Posi-Locks that I still have in service were done in 1997 and are still fully intact without voltage drop or other problems. I don't know how similar or different they are to the Deutsch connectors you've used, but it sounds like you have not used the Posi-Locks. So I'll make ya a deal: I won't comment on the Deutsch line 'til I have some experience with them, and...! ;-)