I thought it was helping, but my tinnitus fluctuates so much and I was disappointed to find that on bad T days, the hearing aid didn't help much at all. I think the days I thought it was helping just correlated with days that would have been "good" days regardless. Also, mine broke during the trial and that didn't bode well for the future. In addition to all that, when I took it out I had the annoying full feeling which is almost as bothersome as the tinnitus.
Keep in touch and let us know how it goes! My surgery was successful and I never had tinnitus (or noticed it, at least) nor any issues with the mastoid cavity for the next 10 years. The T came out of nowhere after an ear infection. Was it the infection? Was it a dental implant? Was it anxiety? Did everything just come together as one perfect recipe for tinnitus? Hard to say. My hearing tests still don't show sensory loss.
You've got a good plan in place in case the tinnitus doesn't go away. My guess is that it will, but you may want to get the ossicles reconstructed anyway.