Just to recap, I've had this issue since I was using B5E/Thunder Blast last winter. Our facility was not run well and the clay courts were wet for months. The heavy balls did my arm in. I've played a few more hours per week lately and that is what I think is really bringing me to a tipping point.
I use the Discho Microfibre, not the Iontec. It probably is the 5th softest multi I've ever tried. I do have a set of natural gut coming tomorrow.
I'm also realizing after demoing something that I did not really believe until now. That extra 1/2" length really does put a bit more stress on the arm. The 7G is comfortable, I just think as I age my arm strength is not there for longer matches. The Exo is the next logical step down in weight. Plus, my game has been based on spin in the past. The Exo really brings my heavy topspin forehand back into the mix.