i'm going through the same thing, trying to find a suitable bike to ride for the street... i thought going from a 1000 to a 600 would do it, but the new 600's are just as crazy fast as the 1000's, since the track has taken away any fun that riding hard on the street might provide its just no fun at all riding around on a super stiff bike with a uncomfortable riding position, doing 45mph knowing that the bike wants to be doing 145mph

i haven't ridden one but i'm very interested to try out a honda cb600f hornet, sporty bike, comfortable riding position, but not so much power that every time you open the throttle for half a second your doing triple digit speeds

s4r would be nice, also sv650, fz6... or maybe look into a motard, although the only really affordable common one is the drz400... maybe a zzr600 if you want to stay with the kawasakis

i understand just what you mean when you say performance is important, but don't try and think of performance as just horsepower... sure most naked bikes or sport tourers might not have the peak hp output that a supersport bike might have, but usually they are based off of a supersport motor tuned to have a more daily usable powerband with more torque... plus once you come to terms with it being ok not to have the "baddest" bike on the block there is alot of fun to be had riding a bike with less power