Keith,
I did download the performance manual. Does it seem strange to you that V2 is lower at higher pressure altitudes, up to 4 knots for the same weight?
Any additive for compressibility, although a small factor at this low a speed, would surely increase V2 at higher pressure altitudes.
From what I've seen, V2 has nearly always been exactly 1.2 V stall, simply because manufacturers want the best runway performance, and while V2 can be higher than 1.2 V stall, this would increase runway requirement.
I understand improved climb. However looking at the reference you provided, I see no indication that the example is for that case.
I'm half wondering if position error corrections for the airspeed indicator can provide an explanation, although the only corrections I've seen for jets at this low a speed were a fixed amount, up 2 knot IAS, and regardless of the pressure altitude. It was only once airspeed became greater than 160 knots that position error had pressure altitude corrections applied (as well as the correction depending on airspeed , of course), and temperature was not a factor.
Anyone?