Unless the bike is a few pounds lighter, I'm not certain it'd be any different than your Tarmac. If it is heavier, then you might not like the perception of how it accelerates compared to the Tarmac.

You seem to be saying the BMC is heavier than your Tarmac. I thought the RoadMachine was suppose to be a pound or two lighter. Even with it's disc brakes which aren't the weight hit they once may have been.