What size of MTT are you talking about? The 45 person ones I've won maybe a dozen or so. Bigger ones like 150 people +, I have a couple second place finishes. Don't play many of those, I don't have the time to sit for that long uninterrupted.
I had one win on Doylesroom against 246 players, a win on Tigergaming against 174 players, recently on partypoker against 2432 players and twice in the past against 1856 and 2267 players and FullTilt Poker twice against 347 and 268 players.
i have won 3 on laddies with over 5000 people and 6 on royal vegas 2 with 10000 entrants and 4 with 1000+ entrants i have also won a few cash multis but i think it is harder to get to the final table of a freeroll not because of the amount of players but u have to play a little different to make sure u have the fish beat before u put all your chips in the middle they call with gut shot draws 7 high flush draws they are nuts because it has not cost them any of there own money to play to win after u get to final table is usually easier on a freeroll tourney