They didn't build alot of Hamilcars, but the ones they built seemed to do fairly well. I don't have the number of armored vehicles they used in Plunder/Varsity either, but I would think you are right, not very many. I have seen the number of 440 gliders used for Varsity, but that was both Hamilcars and Horsas. That was the British gliders anyway. The Americans were using the Waco CG-4s for their landings.