8 Months later and going Great!
Hi ec51, can't believe my thread has re-surfaced. I had the "subacromial decompression" procedure in April (ac debridement and bursectomy), and after 8 months now I can really say tennis is going great. The best things I have found are resistance band exercises, Pilates, being aware of posture, and dynamic warm ups. I have found that a great benefit of all the rehab and strengthening has been much improved power in my forehand and wow, I even hit a couple overhead smashes the other day!
THis forum has been especially helpful as well, with lots of posters who have experienced something similar. The ortho surgeons can say all they like about recovery but you really have to experience it first hand to know how it will go.
In my experience things to avoid are: playing again when there is still significant pain when serving, listening to inexperienced gym instructors, letting a GP give you a cortisone shot!
Best of luck and Merry Christmas to everybody early !