I noticed this effect years and years ago with my first T5, ironically which is now the castings for this one. I noticed it was tight when I washed the T5 in 09 before install and left it in the sun to dry, the input shaft went slack once it warmed up.
Anyway I will measure it all up and see how much actual float if any, and if none, what amount -ve float there is. The specs are 0 float but in practice this might be hard, as shims wont land exactly on 0 and temps obviously effect it so some preload might be good so its not too loose at operating temps, but not too tight the bearings fail.
Spoke to PPG and they reckon depending on the tooth profile they might not have the tooling to cut the custom input shaft. So I asked them more about the set they sell, they said the gears are a lot wider than stock and beefed up. I also asked if using a uprated main shaft with their set would increase the overall rating and he said absolutely and well over 500+hp will be no probs at all. Seemed to be all for what I wanted to use it for and confident I wouldn't have any issues.
Once day I might buy one. not cheap but what ever
I would also consider them having the input made with 26 spline instead of 10 for better strength at the clutch hub.
Interestingly the way he machined the tolerance in the bushes is the final ID size will shrink to correct tolerance once the interference fit is made when pressed into the housing. The bushes also have a non interference lead in section to aid initial alignment when pressed.