Brian, I did not post Xtol is on its way out, just that B&H is not stocking it right now and do people have insight as to why? If it is on its way out, I figure people would want to stock up rather than find out the hard way.
I think DD-X is more like T-Max developer (which is excellent and I use it.)
Here are some other ascorbic acid based film developers:
I maybe totally off here but if I recall correctly Kodak stopped making all their chemistry years ago. I think it was Champion Chemicals that has made all of Kodak chemistry under contrast since then. When Kodak went bankrupt they owed Champion a lot of money. Perhaps until Kodak can prove they will pay Champion for any Xtol they make and give to Kodak they will not produce any more.
Again I know nothing. This is just a guess. Xtol is too nice and popular for me to think that Kodak would actually kill it. But then again Kodak had done a lot of stupid things in the last few years.