My main ist Warlock and I lead our raids since Classic. Surely i'm not the best DPS.. sometimes i miss my cooldowns or push some button to late because I always has my eyes on everything except me but it gets better if we downed bosses a few times.
If I have to raid with my Restoshaman and have to lead, I go crazy... it's nearly impossible for me to lead and to heal.
So yes.. it's possible to lead raids as DPS