Since I don't do a lot of printing, and there is no need to do brown toning in the dark, I try to manage using it outside. I float the toner tray in a larger tray of hot water and have maneged to use the technique down to a 50ºF ambient.
I use Ilford FB MG warmtone and have never gotten tones with developers approaching what I have gotten with brown toner, so I hope to keep going with it.
Gerald raises a good point about the hazards of H2S. Fortunately our noses are extremely sensitive to it, we smell it well below dangerous concentrations, but in high concentration it does reduce or disable the sense of smell. It is also heavier than air and can build up in the bottom of open vessels. The process control manager at a paper mill I did some work in put it succinctly for their facility: "If ya can't smell it, yer dead!"
Freestyle is currently out of Legacy Brown Toner. They called me yesterday and told me to expect
shpmt around May 1st. Apparently the same thing as Kodak.
Kodak Brown Toner...
I have often had to wait for stuff to become available at Freestyle including brown toner before but this one is worth it. At the concentrations I use a bottle will last a long time and I have one over half full and one unopened. If you like it pick up a couple of bottles when available and when you use up the first and open the second, order another. If you have to wait a bit you should still be ok.