I share your suspicions. I have never used either frame (and don't use poly), but it would be the unusual person hearing your story who would not immediately ditch either the lead or the whole stick, and pony up for a new racquet. The real questions are two:
1) Assuming that you will feel better when you stop using the painstick, will your pain return with your old setup?
2) Does the fact that tennis is paying your bills and that you hit way, way more balls than anyone else on these Boards, is it a good idea to back off even further than your old setup (which was not "arm friendly") into a new setup specifically to lower arm stress?
Only you know for sure.
As an aside, I would question your diagnosis of GE since tendonitis should not get better with more use/stress as you "warm up".