The only difference that I have found with new Plus-X v old Plus-X and even really old Plus-X, development wise, is the brand new stuff (latest version) requires SLIGHTLY less development time than the old stuff depending on developer used. With "normal" developers (D76, XTOL, etc) 5-10% less (really not a big deal unless you are processing sheet film and your process is SO TIGHT that you know exactly where your zone VIII's and IX's are going to be EXACTLY). Plus-X can stand 10% either way under/over dev with not a whole lot of heart ache on roll film that you are not extremely tight with getting highlights exactly where you want them for some special graded/alt process paper.
Plus-X and Pyrocat HD are a match made in heaven (my general aesthetic) - 9:00 at 75F for N development. In a tank or tray with agitation 1/30 seconds. Fantastic zone VI/VII/VIII - great for caucasian female skin. For more traditional go with D76 type dev.
RB