I think ya done good.

With respect to fuel, the higher the propane content, the better the cold wx performance. HOWEVER, somewhere around +15F, you're going to have problems no matter which brand you buy. Some tricks:
-Stick the canister inside your shirt and warm it up a bit before using.
-Heat some water in a pan when you first start using the canister, then put the canister in the warm water.

Basically, anything you can do to keep the canister warm will improve performance. Some people will use a wind screen, which causes heat from the flame to be reflected back onto the canister, which can make the performance every bit as good as on a midsummer's day. Others will wrap a copper wire around the canister and run the end of the wire into the flame to conduct heat to the canister. HOWEVER, if you overheat the canister, it will go BOOM and could really ruin your day. Really. You've got to constantly monitor the canister by feel. If the canister starts to feel feel excessively warm to the touch, you've got to cool it immediately.

The other problem with cold wx operation is that the propane will burn off first, leaving you a canister full of butane/iso-butane that you can't use since it won't turn into a gas (until things heat up). If you can manage to keep the canister warm, propane burn off shouldn't be a problem, but like I say, pay really really close attention to what you're doing when warming a canister.

Just some things to consider.