What line of work are you in?
Do you run your radio on a headset all the time.
Reason I say this is that the comtacs I dealt with only had one speaker in each ear to handle everything..... This is a problem if your in any kind of confrontational job (Mil, LE). When the radio keys up you now no longer have situational awareness or cant hear your team mates.
Ive since switched over to sordins or liberators and im much happier. The comms models have two speakers in each ear. One to handle the comms and one to handle situation awareness. LE here.
The other problem I ran into in my line of work was that I primarily run an speaker mic with an earpiece plugged into the side of the radio 99% of the time.
I had to go to a hirose quick disconnect speaker mic and a hirose quick disconnect ptt.
For the comtacs though you would need to have the boom mic, y-cable and a ptt. Which gets very expensive
The parts are all in this link.
http://srstactical.com/all-products/headsets-and-hearing-protection/parts.html?p=2