I tried one of the new turbotech. it's called V2.
It uses a different type of ball bearing. It's soft-ish (not really soft) externally, but still very hard. Not metal.
He explained it all to me at the time. But basically it seals much better, and weighs less too, so responds quicker to the pressures applied.
The internal machining/tolerances of the main body seem more precise too.
I went from the original turbotech, which i had for quite some time, and was happy with, to using the new version about 1 year ago.
It seems like it spools up even quicker.
In my case, it overshoots by barely a couple of psi on WOT, but then settles quickly and holds steady. personally i like it this way. A bit of extra boost early on never hurts
Although i suspect the overboost is caused by my 10 psi actuator, which i installed around the same time. it's pretty tight and caused overboost with the original turbotech too.
Overall, i'm very happy with the V2. It hasnt given me any probs since i installed it. Basically set and forget.
This is the one: