I used XTOL with carefully controlled conditions: a Jobo processor, a densitometer, distilled water. Even so, I got very inconsistent results. With one batch of developer, normal development (Zone 8 at 1.30) came with 8 mins time with HP-5+; with another batch, it needed 12 mins to achieve the same density.(posted 8923 days ago)I called Kodak and they blamed everything except their developer. They said it was my water (which is distilled); it was my temperature (which is controlled by the Jobo); it was improper mixing or dilution; it was HP-5+ (I should use Kodak film was the implication). I have had no problems with any other developer. I am convinced, it was the XTOL!