Totally agree that overall the consensus (and the actual racquets) aren't that different fro the past, with the notable exception of the AST, which actually did change its flex quite a bit with the GT version. If we're being totally honest and knowledgeable, there really isn't anything to "GT tech" that would affect the final product either way. In fact, there are those who would say that there is no "GT tech" at all...just GT marketing. So to pronounce any quality as being present across all GT frames is an error. Despite their all sharing the letters GT in their names, the racquets have little in common. GT is simply their way of creating new buzz around their latest frames (much like Wilson did with BLX after K Factor, and like all the other manufacturers do).
The PD and APD series have long been known to be fairly harsh to many because they are stiff. The AST has, in its GT version, suddenly become much stiffer, too. Not because of GT, but because they changed the layup's stiffness in order to make it play more like the APD. If you notice, they also altered the cosmetics to associate it more with the APD than the PST (which it was associated with in the past). Both of these changes were simply marketing decisions based on the popularity of the APD, which is much greater in units than that of the PST (which they consider a niche racquet). So, you probably will see more complaints in the future about the harshness of the AST GT, despite its previously more friendly nature.
You're absolutely right that the PST GT is not considered a harsh frame. Quite the contrary. But any frame change can cause arm issues (especially elbow), and they did change a few aspects from the previous PST. It's not stiffer at all, but they changed the layup slightly, which most importantly altered the flex pattern and weight distribution slightly. In other words, it doesn't flex any less, but it does flex in a different spot on the frame. These are likely to be what those who have issues with the PST GT are feeling. And then, not knowing any better, they are lumping all the GT racquets together because they share the letters GT (which as I've said mean essentially nothing, other than to denote the years they were sold).
You're right to note the OP's elbow injury, in that these changes in weight and flex pattern are very likely to affect someone with a major elbow injury than the average healthy player, and might not be issues for the typical user. Your advice to check out soft racquets (and specifically Pro Kennex) is really sound in my opinion. But I'd also add that he should take any demo he's really interested in, and get it matched on spec (weight, balance and swingweight) to the last frame he was happy with, as any change in those parameters has a very reasonable chance of causing elbow discomfort just from the change. Unfortunately, flex pattern isn't something that can be changed, nor is it easy to get good, accurate information about it from any source.