I do sets of 3-5 for some and sets of 6-8 for others, but I don't accentuate the negative - just control it, and I lift as fast as I can so 3 secs per rep if that. Most of it in the negative.
I lift pretty ballisticly, I use CAT on just about every exercise I do.
I personally think total time under load is the real cause for growth, and the magnitude of the load. Perhaps TUL over a period of time such as a week.