I mostly use D76 for 400Tx and HP5+. I'm considering changing to Xtol, which I've used and like. I mix Xtol or D76 in steam distilled water, store it in full, dated, 500ml glass or PET bottles, use an entire bottle for up to 240 sq. in. / liter at 1:1, and dump unused bottles at 6 months. I believe D76 used this way is absolutely reliable, but I have nagging doubts that Xtol is not. The failures, so much talked about years ago and not much seen these days, were probably due mostly to the now discontinued 1 liter packages, and to fairly basic user errors, like storing it in the notoriously bad accordion bottles or over-taxing it's capacity (1:3 in Jobos, for example). Nonetheless, I asked one person I consider an impeccable authority whether he would trust irreplaceable film to Xtol. He said not without a clip test. The person I reached at Kodak professional film technical support insists that failures were caused by a manufacturing problem long since resolved (in part by removing the 1 liter packages from distribution). Also, I gather Kodak has changed the way the ingredients are distributed between the two packages, which suggests some tinkering. I know there are many formulae available which purport to achieve Xtol's properties without the risk of failure, but these days I'm determined to use only well-proven commercial developers. Can anyone shed light on this?