Let me weigh away, and good luck with the weight.  ;D

Yeah it doesn't simmer very well. I think I've always said that. BUT neither do some other favorite stoves, I'm thinking of the MSR whisperlight. I have seen the MSR WL produce a better simmer if the cook pot was raised a bit off the burner and the tank pressure wasn't pumped very high. I think that's why I do like the Jetboil's Fry pan for doing fish. Jetboil want you to use a universal pot adapter to keep the Fry Pan's bottom off the burner. The combination of raising the fry pan and the heat exchanger capturing heat near the edge makes for cooking surface without a center hot spot. But you're not using a low heat to fry fish either.

That said I did get, and try, the cook pots JB sells. They also want you to use the universal pot adapter with them. They don't lock-in like the "cook mug" so they're easier to lift off. And although you don't have the boil over problem. I still don't think the Jetboil works very well if you're trying to simmer. Mine is the original model.

Maybe better to go with Cliff "what's his name's" approach and use cozies.