After 30 years using the original Rega arm, I have no doubt that the unipivot 3D arm on my VPI Prime is a significant upgrade. However it sounds a bit better since I added the Dual Pivot, which also solves the possible problem with azimuth because it doesn't wobble anymore. Setup is easier because now I adjust azimuth by turning the screw on the Dual Pivot which is dramatically easier than rotating the counterbalance while try to keep the tracking force from changing.
I don't know why VPI decided to start using gimbal bearings. I think they are just responding to the market and the anti uni-pivot chatter. I say that because when I met Harry W in the late 80's and told him I was thinking about switching the aluminum platter on my 1st generation HW19 turntable to his newer ones with a more vinyl like surface he told me not to. He though the aluminum sounded better but Sota was kicking his butt with its claim that that records sound better on a surface that was more like vinyl. I'll point out that now, all VPIs use metal platters.
