Well I just wasted about 4 decades in the old dark room, printing up a primitive test of my contrast filters, with completely inconclusive results. If you would like to speculate on the results you are welcome to. I think I need to budget a step wedge and in the meantime just figure if it don't print on grade 2, wait.
I printed, from top to bottom, .1, .2, .4, 1, 2, 4, 10, 20, 40, and 80 second exposures. 10 seconds is the first tone that showed up. From left to right, the grade 0, 1, 3, 4, and 5 filters.