My experience with the flex bar is very positive! Had this nagging GE/TE combination for a few months now. I would say a moderate case, which I could and did play through.
. I tried stretching, heat, ice, acupuncture, it would not go away. I found a local distributor for the flex bar. Used the green for a week- TE is almost completely resolved! The GE is much better, but still needs some post play care (ice). But definitely much better compared to before the flexbar exercises.
I think it's the eccentric component of the flex bar exercise that really has a good effect on the injured muscle/tendons.
Oh and take it slow. Do not overdo it, or you could give your other arm TE/GE!