For what I see, there is no really downside with running the AV2 as slave to the CP2E. My only comment would be that since you are are thinking on adding ipads/iPhones GUIs, you might run out of memory, therefore the need for the MMC memory on the AV2. Other than that, Are you looking at the C2ENE-2 instead of the C2ENET-1? are you separating the Crestron network from your home network? if not, the C2ENET-1 should be fine on the AV2 and should be less money that the C2ENET-2 or CP2E.