I'm playing with the idea of making ascorbate version of FX-15. I think it is a good idea to have metol in addition to PQ, but I am more interested in how ascorbate can perform in this type of formula. The key is to seek a good balance between M and PQ or M and P-ascorbate. You see a part of Crawley's intention in relatively large amount of metol and bromide.(posted 8185 days ago)Frankly, with original FX-15, you can get speed comparable to XTOL or slightly more, but I don't know about the "better image quality" part. D-76 1+1 is hard to beat despite the claims people who love exotic ingredients make.
If you like to experiment along similar line of thinking, I suggest making up some batch of ascorbate version of D-76 I posted here before, and adding small amount of phenidone solution. I suggest 0.025g/l as the starting point (in D-76Ad 1+1). I like to use ascorbic acid as a part of the buffering system instead of Crawley's trademark carbonates-borate mixture.