Currently using a basic version of the Jetboil which is about 4 years old. Did a test a found that I got 27-8oz boils out of a small canister. Tests were done at between 5 & 8,000 feet.
In order of appearance I've had: an Optimus 8R, Svea 123, MSR Whisperlite and an el cheapo canister job that I bought for a trip to the Grand Canyon.
Love the Jetboil!! It does about everything I need, easy to use and lightweight. Only drawback I've found is the empty canister thing.