First I must say that I got your latest postcard, and it is wonderful.
Second, If you like the polywarmtone I bet you will like the J and C Museum.
It is the same paper that I did that tree postcard on. It is graded, but there seems to be a little latitude in the paper where you can control the contrast slightly by varying developing time. I personally am glad that I don't have to order the stuff from Europe anymore and can get it in the states.