I almost always use a basic form of clutchless shifting....
Always when slowing down to stop at a stop light, I wait to feel the point where the shifter will just slide out of gear.
Its one less clutch press which can help, in heavy traffic.
I tried some full clutchless shifting today....you have to be really confident and exact to get it right. I got some grinding, and probably wont be doing it much.
I dont think Its not any worse on the clutch than regular shifting if done right. (normal speeds, no grinding or clunking or lugging)
Its not powershifting.