I really don't disagree that the results are not dead on as they would be with C41. The negatives do print very well, and the process gives very repeatable results. For that reason, I posted what I'd found. I thought perhaps that anyone that had experimented with Dignan's formula might find that this worked better for them, as it can be tailored to each film type and easily altered for contrast. I would think that it would be quite suitable for XP2. And I plan to continue to tinker with it in hopes of finding exactly the right amount of bromide and iodide to make it more acceptable. I wouldn't for a moment suggest that it matches or exceeds the quality and results from C41.
By the way, when I worked with Dignan's formula, I found that doubling the carbonate and the CD4 helped a lot, and I also found that Kodak films liked some potassium bromide and not potassium iodide, and the other way around for Fuji. Had some success, but not enough to continue fooling with it. I liked the one shot small chemistry approach better.