I've got just over 2000 miles on my 05 ZHP here are my observations.
In casual shifting, ie less than 4000 RPMS, this thing is as smooth as butter! I also have a DIY clutchstop - which was in my opinion the GREATEST mod ever - well worth the 2 dollars. My only complaint is that the shifter still feels a little notchy sometimes. It's almost as if the clutch hasn't completely disengaged or something. But I'm sure that's not it - otherwise the car wouldn't be starting (clutch not in far enough). Other than that, the car is simply a dream to drive. It's so smooth, people are always telling me how smooth the car feels - even with the stiffer suspension. I haven't noticed the idle being too rough though. Maybe because it's nice and warm here in Texas