headset mic

Hello pshybear.  I faced the same problem, which was worse for the original Voicelive.  As you mention, adjusting the Gate function will help, especially in Manual mode.  I have several great microphones (Shure, Audio-Technica, EV), but when using the Voicelive, all had the same problems with cross-talk and feedback.  In my case, it was often the result of having to share small stages with the other musicians.  There are several good headset systems on the market, but after a lot of checking around, I ended up buying a headset and a stage mic made by Audix.

1. Headset – Audix model AUHT2 HT2.  It works with a wireless system, or with a wire using the phantom power supply (model AUAPS911 APS911)
2. Stage mic – model AUOM5 OM5

I bought them from BH Photo (http://www.bhphotovideo.com), which was the best price at the time.  They are not cheap. 

The difference with these models is the extreme signal rejection due to a very tight super-cardiod polar pattern.  It is specifically designed to minimize/eliminate feedback problems.  Check out the details on the Audix website (http://www.audixusa.com)

While it sounds great and does the job in eliminating feedback and most crosstalk, I ended up not using the headset on stage, mainly because I also use an in-ear system - too much on my head.  After some testing, I ended up concluding that the OM-5 works just fine in a live situation.  Both models require a different technique.  You have to be very close and straight-on to get a clear signal.  Takes a bit of getting used to.

Having said all of that, some of the problems you are hearing with harmonies may also be caused in part by over-compression.  I addressed that issue in a response to one of your other recent posts. 

Hope this helps!  Good luck with your decision.