Hello hornylittlepuma,
Actually I have no experience on both types you mentioned, but you can use an adapter chord which converts high impedance(civil) to low impedance(military). Most of the time I fly EC145 and BK117B2(low impedance) and when I change to B412(high impedance) I connect my helmet to the adapter chord. I use it on my helmet now for more than 3 years and I never had any problems with it. It's easy to handle and a microphone change is not required. I bought mine at Flight Suits.
Kasif