Sorry to blow the dust off this after so long, but it's an interesting thread.
Some speeds (V1, Vref etc) are related to runway length in its various guises.
Others (V2, VMU, etc) are related to aircraft weight.
To mix and match assumed temperature V1s and V2s is mathematically invalid, which would be fine if it had been proved by flight test, but it hasn't.
So, we should all be using actual speeds for actual weights.
Following an engine failure, do you want to use a 'wrong' V2, and thus invalidate your performance calculations? (V2 has ONLY to do with AUW).