I'll admit, I usually left CoH for short periods to try out "the new mmo", but it was the only game I always came back to.
I did this too, but I didn't leave to do it. Or more correctly I never unsubscribed, I'd not play CoH for weeks to try out some new game - Champions, DCUO, Aion, WoW, Secret World... but I always knew I'd be coming back, even before I left. So I didn't bother cancelling the subscription because chances were I'd be back before it would've run out anyway.