This is confusing.As for the stock cabs. The "None" mic, not to be confused with "Null" gives the sound of the cab without any mic model coloration. RTFM folks.
Most of the stock IR"s are captured with mic's normally used to mic guitar cabs in a studio; not reference mics.
The mic pick list in the cab block is a simulation and doesn't change the mic used to capture the IR.
You obviously can choose "none" with the new cab packs too... right?
And you are not correct about "null". Null adds zero coloration too, just like "none", the difference is "null" enables other controls in the cab block, e.g. proximity. These controls do nothing with "none".