Are the Kenda's smooth too?
I've been using 700 x 40 semi-slicks (Michelin Citys) on my hybrid for about a year now and they are plenty fast for me. I pump them up hard. The rolling resitance of them is no problem at all, and I do mostly brisk road rinding. I do not feel as though they are too slow on the road (for a hybrid). However, this is compared to 26 x 1.85 semi-slicks (same type of Michelins) I used to ride on my MTB on the road. Seems like there might be slightly more rolling resistance since your 700 x 40s are wider than what you're used to. I'd give it a month or two of riding to draw your conclusion. The 40s may be doable.