Well here's a tiny data point ...
The main concern seemed to center on 400 Tmax, but as more info, such as emulsion numbers, came out, there was some 400TX listed. Wouldn't you know, the fifteen tolls I had bought for a trip were from that batch. So I contacted the Kodak person via email. He told me there had been very little indication of a problem with 400TX, but to send him my snail mail address, after which he sent me replacement rolls. I have since shot several of the original rolls that were in question, using them on silly local projects that I could re-shoot, and have not seen a problem.
I also hauled a dozen or more of the later replacement batch on a 3.5 week 5800 mile auto trek out to southern Utah, northern Arizona, northern New Mexico, etc. in July. I kept the film in a couple of those insulated bags that neatly fit a six-pack. They spent their time in the back of a modest sized SUV, and air temperatures on occasion were well over 100ºF (although low humidity). The insulation would hardly keep the film from reaching the temperature extremes, but at least slow the rate of change a bit. I have seen nothing untoward in the rolls I shot and processed. I took, and used, about 50% Ilford HP5 Plus mixed in with the 400TX (not being an all the eggs in one basket kinda guy).
I am left to suspect that the 400 Tmax problem was some unholy combination of the backing paper/ink out-gassing *and* the particular chemistry of that film interacting. But that is a barely educated guess, nothing resembling true knowledge. The only "real problem" I am currently aware of with the latest backing paper is that it is lighter printing and harder to read in a 'red window' camera, and unless there have been more recent changes, they dropped one row of numbers that were used by some 6x9 format cameras. The latter is a true problem if you're shooting one of those cameras. My Ercona II is fine with the new stuff -- haven't tried rewinding any on 620 spools for my Brownie Target Six-20!
My Bronica and Yashica TLR don't need the numbers at all, my Perkeo II 6x6 just needs to find '1' in the center row.