While these new mixtures are slightly better than pure Iso, they still suffer from the cold. There is significant drop off in gas pressure released as the temperature gets closer to the boiling point. They are NOT fine down to zero F. In fact below 32F one can already notice the effect of the ambient air temperature on the performance of the stove.
As the canisters release their gas ( as long as temp is above the boiling point) the pressure drops and this cools the liquid even more) potentially causing the canister's liquid to stop vaporizing.
This isn't to say one can't use them at zero F, but one must keep the canisters warm by sleeping with them, placing them in water, or some other technique. Simply, the claim that they are no longer an issue down to zero F, is misleading at best.