I personally know the owner of Sigtronics, you know that T-28 in their ads? Thats his, he has a Sig intercom in it, and uses his headsets. Same goes for his T-34 and 210. I installed a 200s in a Ercoupe and LOVE the simplicity of the wiring and how well it worked in the high noise environment.
The main thing I think he is missing is an audio selector built in ala PS Engineering, but he's an stubborn old fart in that way and won't make one, even with continuous hinting... So off I go to install another PSe 4000 Audio panel in an airplane...
If you don't need an audio selector, I'd take a Sigtronics over PSe just because of their wiring harness and the fact that everything is built 15 mins from the Brackett Field where I'm building...