YESS!!! I got everything working schweet!
thanks for the advice guys. i went over everything and here's what i found:

swash perpendicular to shaft (correct range of motion in both modes, no binding)
blades dimensionally symmetrical (no warping and similar stiffness in all directions)
flybar/head balanced on heli (on the heli as you said, by loosening the collar))
blades balanced & CGs matched (cg of both blades are located in the same distance from the grips, and balanced as normal)
sloppy movement of one of the bellhilller arms
sloppy movement on the flybar hub

after i tightened down the arm and hub screws, everything moved smoothly, but not as free as before. so i added silicone lube to all the friction areas and it helped a bit. now all my vibrations are gone and the heli hovers hands off for 3sec, instead of 0.5sec. it appears better to err on the side of more friction/less slop with bellhiller arms (versus more slop/less friction). i always knew helis need to be very precise, but man do i know what that means now! i had no idea what my heli was trying to tell me until now.

(jealousy) i was thinking about the hb king too, but it seemed like parts were hard to find. i bet that tail rotor is going to be way quicker, woohoo! i'm going to hold out with my cp2 until i can afford (and deserve) a Trex450se.