Is the Kashnarak worth taking if you do not have Wyches to control him? I was thinking he could be a useful distraction running about the board as my main force would have the speed to avoid him.

I've not used one before so any suggestion are helpful

I've used it ones. It was good because my opponent placed an garrison to close. It died to their shooting (powerful shooting formation) but the formation had to use its overwatch so I could later go in and break the garrisoned formation without fear of retaliation. It was the first time the guy played dark eldar though so he probably didn't really know what he was facing. A more learned opponent would not give that kind of freebie.
I don't think I'd take it without whyches though.

Yeah I'm thinking the same to be honest. I like the idea of the Kashnarak but I don't to take a wych unit just to babysit him