Bit off topic but I've sent an email with a few questions to Derek at HTS LLc about his changer. Biggest issue I see is its ability to properly grip the tool holder. If I'm right on how I see how its done,( ball bearings pressing agains the ramp on the tool holder to draw the taper in) then I can't see how enough upward force is applied to make it really positive grip. That,, and the fact that the centrifigal forces on the balls will lossen this grip at speed, which is the opposite to what you want. I know its over the top but read up about HSD and NC5 holders to see how they deal with the issue. If the design was such that the centrifigal force increased the lockup the fact that the spring is rather weak is not an issue anymore.
Just my $0.02
Cheers
Mark