Although not in exactly the same situation as you are, after my first AN surgery I retained 20% of very useful hearing (100% speech discrimination) in my AN ear. My neurosurgeon and ENT both felt I would benefit greatly from a hearing aid so I paid over $2,500 for a MicroTech7 hearing aid. I had some improvement with it, but the device itself was very uncomfortable and I went back to the audiologist multiple times trying to tweak it for better hearing. Long story why, but I switched audiologists who felt this device was just not the right one for me. She talked me into getting a Widex Mind hearing aid (for an additional almost $3,000). What a difference!! I could hear so much better and it was a tremendous boon to conversation in small groups.
Unfortunately, I fell into that very small percentage of people who experience regrowth of my tumor. All of the doctors I consulted who reviewed my MRIs and audiograms, agreed that I would lose the remainder of my hearing no matter what I did ..... nothing, radiation, or surgery.
All of the above is to say, that some of your decision depends upon how much money you are willing to pay for improved hearing in the short term. As you know, ANs typically are very slow growing ..... but the direction it is expanding is what determines how quickly it affects your hearing. I guess I would ask my doctor how close to the cochlea the AN is now, which would also have a bearing on length of time. I am not a doctor, so I would certainly ask my doctor(s) their opinion before I spent $3,000 on a hearing aid. To my knowledge, it is a rare insurance company who will pay anything on a hearing aid because it is not considered a medical necessity.
Finally, although I spent waaaaaaay too much money for two hearing aids, the three years I wore a hearing aid certainly improved my mental health.
Best thoughts.
Clarice