I use it for all my B&W. FP4 rated at 250 and Neopan 400 rated at 640. I love not having to be overly concerned about temp especially as I shoot approximately 30-75 rolls of B&W per week during my peak periods. Very consistant negs which are printed on grade 2.5 Multigrade with Agfa Neutol WA developer.(posted 8135 days ago)Kodak Tri-X 35 is rated at 1600 and the 120 pro is at 1000 so you may want to try a slower film. All the B&W images on my site www.georgeweir.com were processed in Diafine. There's a couple of thousand there just now, most are smaller for speed however there are a few larger ones at http://www.georgeweir.com/pages/photo-essay-home.html
Anyway, give the diafine a try, I believe that you will come to swear by it like your friend. Then buy a couple of two and a half gallon containers with floating lids and make your life that much simpler.
ALl the best George