I'm pretty sure the comps are silver soldiered on at the factory, making they nearly impossible to remove without destroying the comp although I could be wrong as I haven't tried to remove one. I use a fresh 6" barrel with a new cone comp, cut it to length, thread it, then attach the comp with red Loctite.
I think the three port is an improvement over the two port, I have a custom Limited with the three port comp and three 5/32" holes I'm getting ready to shoot for the first time so stay tuned