Well, seems that something is NOT working with gripforce clutch. So why make same mistake twice?
Utlimately I do not know what the problem is until all is taken apart...but at $500 a run I really want to make sure there're no weak links.

 

Finally I got around to fixing my car.
I had put in Exedy Racing Stage 1 clutch, ACT Streetlite Flywheel, stronger clutch pivot ball, Nismo pilot bearing and new complete propshaft.
Car is cured of all problems.
-Poor shifting-to the point I had to turn engine off, select gear and start the engine again. Problem-clutch didn't release completely leaving input shaft turning. Seems that F1 Racing clutch construction is not robust(Exedy is much more solid and "hefty") enough to take on the heat even under normal driving-it was better when icy cold or even after car sat for a week. Multiple clutch bleeding procedures didn't alleviate the problem. There was little wear on the disk after 10K km of normal driving and it seemed to wear evenly. No heat spots on flywheel.
-Vibration 1-with clutch depressed and blipping the throttle there was strong vibration at 2-3K. Either flywheel was not propery torqued, or flywheel is crap. I will not be taking it to balancing machine. If someone wants it-you can have it for $50+shipping as is, no warranty whatsoever. No vibration with ACT flywheel-at any rpm.
-Vibration 2-at speed, not dependent of engine rpm. Seized yokes and lost weight on propshaft.

Verdict 1-F1 Racing(gripforce clutches) hardware is not up to sniff in G35.
I hope new combo will last and will not develop any problems for the next 4-5 years.
Verdict 2-Nissan makes crappy propshafts or they made at least 1 crappy propshaft and I was the one to have it.

 

thanks for the update, greatly appreciated

 

about to do the Exedy Stage 1 clutch, ACT Streetlite Flywheel combo too, hope everything goes well.

 

love them, 2 autox, 2 track days and lots of city driving.