Well, the subj of hearing aides has been well explored. I offer my experience (12 Yrs) and thoughts now, probably as a final post from me.
I do not advise dealing with Costco on hearing aides, They are a good store, but they cannot get well-experienced Audio specialists for what they offer as wages, so there you are, being required to go to a lot of trouble.
First point:
Closed Ear molds are obsolete because of four reasons: a) they create an unhealthy ear canal biology because they seal the canal and cause moisture issues I) fungus growth, ii) skin reactions iii) itching; b) they are very difficult to fit accurately because the molding process of inserting the initial mold substance itself distorts the ear canal and produces an inaccurate mold master; c) sealing the ear canal causes loud noises of mastication to drown out all other sound when you chew; d) The ear canal changes shape if you lose or gain weight, so the mold doesn't fit anymore.
For these 4, and other, reasons the hearing aid makers have developed better electronics to permit "open mold" (domes) to work better than "closed mold" technology can work..
The principal problem which the industry has solved is to prevent acoustic feedback (squealing) caused by the sound produced by the aid when an air leak exists between the ear canal and the receiver of the hearing aid. Days gone by required a perfect seal (closed mold) between the ear canal and the outer atmosphere. The newer technology hearing aids have electronically programmable anti-feedback circuits which cancel squealing before it becomes audible to the wearer.
The (dome) ear molds, called "open molds" allow for a high boost of sound volume without feedback, for full ventilation of the ear canal during wear, so no mastication noise, no loss of your environment sound awareness and a much more natural hearing experience, without unhealthy ear canal circumstances. THEY ARE MUCH EASIER TO FIT, REPLACE AND CLEAN. They are cheaper by far, requiring nearly no adjustment or fitting, except initially.
The electronic improvements made to modern hearing aides are many. Custom setting and re-adjustment of several hearing programme profiles for each user's individual hearing loss, and for each different sound environment These programmed profiles are adjustable and re-adjustable, by a hearing audiologist, many times, (requiring a visit to the audio clinic) Upgrade hearing aides have remotely controllable settings, for different listening circumstances. Very useful, they are.
I repeat that you MUST have an experienced audiologist in a dedicated hearing lab. Costco does not have those. They are slightly cheaper than a dedicated audiologist business, carefully chosen,, but not satisfactory in the end, IMO
My aides are made by STARKEY. They are guaranteed for 5 years. My Audiologist has been in business for thirty years. Her lab is comprehensive, complete and fully up-to-date. She is patient thorough and painstakingly thoughtful. She explains things. She answer questions clearly. She does not prevaricate at all.
I have visited Costco. Their people try very hard, but they just do not have the depth of experience, aside from a college degree, that one needs to do a good job. They follow pretty rigid protocols, not always the best thing. They do not have the seasoned experience to know any better...and the company dictates what they can do to make you happy. Money-back is not a solution policy, it is a sales gimmick...it is a run around, too.
I never want my money offered back! What I want are good, effective, comfortable hearing aides..and not a lot of run around BS.
That about covers it, I think.

:thumbsup:
JIX