alin,
I gave super slow rep speed a more than fair shot. I was doing about a 4-6 second negative with a 2-3 second positive. I trained like this for about 12 weeks. the end result was a huge loss in strength. I thought I looked a little harder(but I may have just been telling myself that so I wouldn't feel so bad about get weak)
any way, i went back to an explosive positive with a controlled negative(as long as the negative is controlled I think the weight should be lowered quickly, probably 2 seconds) my weights are improving again and I feel better when lifting. so I think what you have been doing sounds good. I would not focus on a negative rep count simply lower it with control.
hopefully LATS and magoo will add to this because I agree with their beliefs concerning rep speed.
hope this helped a little