Epilogue:
Well my 2nd Wouxun KG-Q10G radio is finally fixed. Buytwowayradios sent it back to me untested ie. they did not open up the radio to do any visual inspections or continuity testing. They plugged a programming cable into the radio and said it would read/write to the radio consistently. I have no idea how many cables they went through to find one that worked, but they did send that cable to me along with the radio. After I got the radio back it did indeed work with the cable they sent with it. I even bought another Wouxun cable and it works as well.
Then I tried using my rt-systems software and cable again.... and again it would only connect with the first radio but not the second one. Since buytwowayradios would not replace the radio under warranty I opened it up myself to have a look since the 'warranty' was useless anyway. After a good look I found the upper 2.5mm phone jack on the PCB sat farther in on the board edge than the lower 3.5mm jack. Those two make up the 'mic ports' in the side of the radio. They used two individual jacks instead of the more common dual phone jacks I often see.
I tweaked the upper jack to get it to stick out a hair more (not much ~ 0.020") from the edge of the PCB into the radio case so the opening was closer to being parallel to the lower jack opening. After reassembling the radio I redid all of my previous testing and now both radios work with all cables and both software packages. Even mixing cables between the software packages... it all works now.
So to celebrate my now voided Wouxun warranty on a one month old radio, I bought myself a second Yeasu VX-6R radio (NOT from buytwowayradios) and just did a MARS mod on it, which is what I should have done in the first place. Once bitten...