I do print on MCC 110, and I do use the (apparently similar?) brown toner, I just haven't tried them together. When an image calls for a warm tone result I usually print on MGWT which responds beautifully to the toner. I use MCC 110 for neutral tones. It DOES respond in selenium, but if I let it go as far as a noticeable color change I don't care for the purple color. I stop just short of that with a slight cooling (to neutral from very slightly warm - as someone, I think Drew, commented here and I have found to be true, it doesn't seem to really be capable of a true cold tone.) I've never tried to split tone it either.
But I do plan/hope to be doing quite a bit of printing in the next several days, some of it on MCC 110 and some on MGWT that will be destined for brown toner. If I get a chance I'll try it out and report back. I'm curious myself now. I've no idea about the sulfite.