Will do Andy. To be fair, I use VERY dilute brown toner because MGWT responds so strongly to it. I LOVE the look I get with dilute brown toner and MGWT. I can go stronger/browner if I want, of course, easily getting what looks very much like a regular sepia toned, but with a light touch on it I get rid of the slight green cast and move it to a slightly warm brown, which I find quite nice for portraits, old wood etc. This is what I used above - that's 1/8 ounce of toner concentrate in a quart of water. OTOH, I also toned some Arista Private Reserve Pearl (aka Adox MCP 312) with the same regimen and, while I don't like the color produced, it certainly does change color.
I'm going to try the Arista stuff in both much stronger brown toner and in selenium. I keep selenium mixed at 1+19 for use with MCC 110 and some other papers, but my guess is this stuff will take a much stronger solution.
I think they have a winner here. I hope they decide to continue supplying it, and in 16x20 size too. I'm not set up to print larger than that and I can always cut down smaller from 8x10 - I think some images would look extremely nice printed to 5x7 on this.
Great idea about marking the back - I'll start doing that next time I use it!