So I picked up some Ilford XP2 Super in 120 for my Mamiya and I was reading about pushing/pulling the film. Here is an interesting bit of info I found, is it true that you do not need to change development times if the camera is set to speeds between 25 and 800? Meaning you can push and pull on the same roll? I tried searching but couldn't find anything to back this up.

I normally use Ilford XP2 Super over the Kodak product, as I find it to be superior in sharpness, scanning ability, and lack of grain. I shoot anywhere from 0-50 rolls a week of XP2, and for those of us who scan our own film, it is IMHO, the best film out there. XP2 is made by pouring 3 layers of material to make the film. This is what gives it the variable ISO structure (I think). Ilford recommends shooting at either E.I. 25, 200, 400, or 800. Mine is a simplified explanation, but by shooting at different ISO's, you are activating different layers of the emulsion. I am sure that Kodak has a somewhat similar process, but I find that the XP2 is the one that gives the best truly variable ISO results, with NO CHANGES IN DEVELOPMENT TIMES!! AMAZING!! I can actually shoot 4 frames on a roll at E.I. 25, 10 at E.I. 400, and the rest at E.I. 200 - with no change in processing. I find this unbelievable - it's like digital film! Whatever type of coating layer it has, it scans very nicely too. Again, negatives shot at E.I. 25 will have the best detail and sharpness, but will be the densest. It is best to set your scanner to scan a positive (even though you are not), and then change the result back to a negative in CS3 once it's scanned. This is recommended by Ilford and other experts, and will hold much better highlight detail this way. I have used 400CN when I am out of Ilford, and it's pretty darn good, but it's not quite the same as XP2. The XP2 is sharper with a little better detail. I was just reading a test of the 3 C-41 B&Ws in the latest issue of a photog magazine, and they concurred that Ilford indeed, tested as superior. I cannot find the issue, I believe it was B&W Photography, or one of the Canadian magazines. Try XP2 for yourself, I'm sure you will love it. It has saved me amazing amounts of time by being able to be processed as C-41, in one of those giant computerized machines. I think the quality is a lot better this way too. I had been having a lot of headaches with hand processed B&W and it was making me nuts (and broke). There are a lot of different B&W films with a lot of different looks, and you won't want to abandon that entirely, but for what I do, this stuff is fantastic.