The reason why I asked this, has just become moot (at least for me).
I was trying to install W7 from Lenovo Recovery sets onto my M900 Tiny, which has a Skylake CPU (i5-6600T).
I first tried to install from a CD/DVD set from a
T460 (which has Skylake), but that install failed.
Apparently from Skylake CPU onward the W7 USB3.0 function is no longer supported!
The above is the set I wanted to combine, to then copy it all onto a bootable USB-key.
Next I tried a
T450 W8.1 Lenovo Recovery using a USB-key.
This one installed, my guess is that it has proper/good enough USB3.0
However, Windows wouldn't activate, even with a W8 key in BIOS.
Digging through my CD/DVD pile, I found an official W7 Lenovo Recovery set for a T440/T440s.
Having nothing to lose, I figured, why not try this?
Lo and behold... it worked!
Right now it's doing the finishing of the install (will probably take a few hours).
Before I started this latter install, I compared the CD/DVD contents between T460 and T440: DAY and NIGHT difference!
Anyway, I'm happy right now and will report on the end-result later.
Update: it failed again, (no) thanks to Intel removing W7-USB3.0 support in the (Skylake and newer) CPU. 