Welcome to the forum Joel.
I would be very surprised if the Integra couldn't handle the 4ohm load of the M80s, since the top end Onkyo's appear to be able to handle them just fine.
Have you looked in the Hearing things forum to see if there is anyone near you so that you could audition the M60 or M80 without purchasing first.
Sounds like you have a very nice HT planned. I think we would all like to have a look once you are done so please post some pics of the build up and final product regardless of the speaker purchase.
