Just loaded up a roll of Phoenix I. Reading back through this thread, it seems like the best results are coming when metering at EI 16, and following a development routine that looks nearly identical to the way I process Ektachrome 100 in HC-110 and ECN-2 chemistry. Looking forward to seeing the results.
I've got myself a bit of a stash of Phoenix I after buying a lot of some 100 35mm rolls (at about 5,50 euros each, which included quite a few rolls of only recently expired Provia and Velvia 100), I think I'll try this reversal method at some point as well!