Would this work well with the pocket rocket, giga power etc?

They say it will, but you won't get the same efficiency as with a full Jetboil system. Both the PocketRocket and the Giga put out much more BTUs, so just watch the cozy. Unless you're looking mostly for the heat indicator, neoprene doesn't really add much to the process, except maybe for marketing , although the heat sink will give you a somewhat better boil time. For my money, I would get a Snow Peak Trek 900 or 1400 with either of the stoves you mentioned, especially since the 1L Jetboils will only handle 1/2L of water at a time.

I stand corrected Matt. I just read a review below (see review by christian.f, and comment by Dan). Dan stated that he uses this cup with the pocket rocket, and both seem to recommend them. I could see how these cups would be nice since they have the neopreme sleeve, a handle, and a lid.