Yes, I agree with all that Mark has said. I have never yet tested any Lipo which really can cope with a continuous discharge of >35C without showing excessive stress such as sag and recovery due to self heating or excessive terminal temperature.
John Julian has done alot of investigation into how the temperature coefficient varies in different packs and if you look at the plot he has done in the link below you can see how different lipos vary over the temperature range. The Revo 60 is a case in point; high IR at low temperatures but very low at high tempearures. This means that it will be outperformed by much lower C rated packs at low temperatures.
I think the best you can do is to try to compare IR values at or near the temperatures you will operate the packs at. That may be difficult, but if you do you must ensure you are at the correct and, very important, the same temperature for each pack.