We came with this variant to help the fact that a pro-cylon sympathizer is basically a cylon without the coolest cylon powers, which is kinda boring. This variant might need a twelfth You Are Not a Cylon card if the full six players with B&B are in play, you can use the Sympathizer card for this (treating it as any other Not a Cylon card).
Basically, instead of having the You Are a Sympathizer card, you wait for the Sleeper Agents phase, then you add a You Are a Cylon card (if all resources are in blue), or a You Are Not a Cylon card (if at least one is past the halfway mark).
We haven't tested this thing yet, because the next game we played was a 3-player game (brutal, centurion loss at distance 1, after barely averting damage loss at distance 0), and those don't use a Sympathizer.
I'm seeing that apparently this helps the Cylons more (a third [or second] full Cylon, with the power to stay hidden, a revealing power, a supercrisis card, and being able to activate the fleet, as opposed to a human that just skips the brig). OTOH, this puts a stress on the human players in that if they jump to fast, going for the minimal four jumps, they may be in trouble, but it means they were doing well so far (sucks to be at 5-5-6-7, but if Cylons manage that, they deserve the win). If they turn a resource in the red, they still give the cylon a target and it doesn't seem to change the game much. So it may need some tweaking.
Let's see what you guys think about this one.