I've always been a ball head user and for my 8x10 i recently bought a manfrotto 488RC4 head. Its lovely.. smooth and locks down solid.
I also tried the giottos heads and they dont work at all. they didnt even lock down tight, i don't get it, they are rated 20lbs and could hardly carry my 12lbs camera.. so i bought the manfrotto, couldnt be happier.