Anyway, back on topic......
With advances in turbo technology the makers have also moved toward a longer life bearing, that of the ball bearing. While there may be some evidence that a BB will spool faster, I consider that is due to the improved geometry in the modern turbos running BB. I'm yet to see any real testing that proves that exactly the same turbos except with journal or BB would be very different. In fact, the journal, running perfectly is only riding on a film of oil, while a BB has to also accelerate the bearings at a greater radius, and so would by every engineering principle be slower to spool if everything else was equal.
Given that cheaper highflows aren't as economical as they used to be when Slide did them I would Highly recommend the GTSS or 2860 setup.
Also common practice is to assume between 25-30% losses through drivetrain and tyres on a dyno unless it is a direct connection to the hubs, such as Dynapack.
No sense arguing with Ash, he only repeats what others say, although he is an authority on prices, especially for others doing the work, so worth listening there.