I missed this but I have just replaced my knobblies for City Jets and there is a real difference. OK, I am not fit enough to exploit the performance side of it (yet) but apart from losing the softer ride, they are more responsive, very, very quiet on the road and feel great. I do not believe you will regret it at all, I didn't and I know nothing lol. My thread is here, loads of advice and what I thought about it when done