Well, Patrick, the Reactor and the Windburner are much the same in that they employ the unique radiant burner instead of a flame. One difference between them is that one can re-set the burner in the field if you overheat it and it shuts down. This improvement is now on the Windburner. Jenny Askey posted about her experience in Yellowstone last fall, where her Reactor abruptly shut down, leaving her stoveless. It had to be sent to MSR for them to re-set it.
A couple of years ago we were able to borrow one of the pre-release Windboilers from the local MSR rep.That’s what they first called it, before they were forced to re-name it the Windburner. She asked us to not fire it up, but we were able to evaluate it somewhat, weigh all the components, etc. I wasn’t much impressed – it was heavier than my 1 L. Reactor by a couple of ounces, it seemed pretty top heavy and probably not so stable on uneven ground, but it DID allow one to reset the burner if it failed in the field. I couldn’t see investing in one of those stoves, since I am seldom in conditions where I need the benefit of superior wind resistance. I will only use my Reactor while truck camping, where I can bring along backup stoves in case it shuts down.
My favorite simmer stoves include the hard-to-find discontinued Coleman F-1 Powerboost, which simmers superbly but weighs 6 ounces. Another one that impresses me is the stove that came with the Jetboil MiniMo. It also simmers really well. It has a narrower burner head than the Powerboost, but it weighs ~1.5 oz. less. Another one that I’ve recently picked up is the Fire Maple FMS-116T stove, which weighs a scant 1.8 oz.. I’ve only tested it on my patio and while truck camping, but it’s quite able to do a very low simmer. Its burner head diameter is half way between the Powerboost and the MiniMo stoves. And, heck, I’ve even been able to do a righteous simmer with my BRS-3000T when using a MYOG heat disperser.
I probably should note that I did try to get my Reactor to do a decent simmer. I had to do a modification to be able to position my pot 3″ above the radiant burner head. It worked well for the first few bowls of soup I simmered on my patio. Then it finally shut down while I was doing another. It was likely some sort of heat feedback thing of some kind. I took it back to REI as a return, but I made the mistake of telling my pal that worked there how I screwed it up. The word spread to the MSR rep, and I expect that I’m now on their “Bad Actor” client list.