One thing you need to take into consideration is the Pocket Rocket is an upright canister and is limited to about 20F (minus for what ever elevation you will be at), that is of course if you use a good fuel blend and sleep with the thing.
Hikin Jim on here has a blog and he is a bit of a stove nut, he knows all the numbers and comparisons plus tested many of the stoves out there
Hikin Jim's site is great! I've been there multiple times. I'm just trying to evaluate the best solution for a 4 day backpack. Most all my meals consist of boiling 16-20 oz of water. Maybe 3 times a day and maybe one or two 16 oz for coffee in addition. First and foremost, I want to make sure one 20oz bottle or two 8 oz canisters will last 4 days. I believe they will. I seem to get 15-20 "boils" out of one canister.(this with varying volumes of water being boiled)
Last camping trip we had temps in low 20's. I had a Coleman canister which is propane and butane mix, NOT isobutane. It sputtered some and seemed to take longer to boil but that could have been because of the water had ice in it. The second night, I put the canister in the bottom of my bag and the following morning I had no sputtering. I believe with the Isobutane/propane mix, I'd be good down to 20 or high teens, especially if the canister was kept overnight in the bottom of my bag. This seems to square with Hikin Jim's info.
If two canisters or one 20 oz bottle is comparable and either will last 4 days with fuel to spare, then the Pocket Rocket would be the first choice based on weight alone. Whisperlite would be the choice if anticipated temps drop below 20�.
