If you go to Costco, I suspect in 90+% of the cases you will be well treated. They have fitting standards and with the exception of the odd rogue fitter, they are followed. Keep in mind that in your first audiogram session most of the time will be taken up doing the very thorough testing that they do; complete audiogram, bone conduction tests, speech in noise tests, and checking your eardrums for any damage. I may have forgotten a few things. You can make your decision at that appointment on which aids you want to buy, but there is not going to be a lot of time to try a few and see what you think.
If you want to test store demo units they will probably let you, but there will not be enough time in the first appointment to do it properly. If you want to compare different models they should really be REM fitted (a test to actually measure how much gain they are putting in your ear canals), and that takes time. You should also ask them to use the same fitting formula, like NAL-NL2 to be programmed in all the aids you test. Then you will be comparing apples to apples. Short story is that if you want to compare aids properly you will need to set up a second appointment. If you don’t want a long wait, it is better to book that now, rather than do it at the first appointment. They may even give you back to back appointment slots if they have them.
Once you select the ones you want they will order them, and that generally takes a week. When they arrive they will need to program them for your loss and do the REM testing again. Next you try them at home and it would be wise to make another appointment to do any further fine tuning. If anything is changed in the fittings, (open to closed, or vent size changed) then the REM should be done over again.
As for brands I’m not entirely sure how similar the Phillips HearLink aids are to Oticons. Others may be able to help you with that. The aids that are very hard to pass up at Costco are their Kirkland Signature KS9 aids which are basically Phonak Marvel M90 premium level aids. They are comparable to the Phillips aids and Oticon, but cost $1500 a pair.
Costco doesn’t really do trials where you get to take the trial aids home. You have to buy them to try them, but have a no questions asked return policy for 6 months. If economics are any concern, then I would just buy the KS9 aids and try them. If you don’t like them after they attempt to adjust them to take care of any concerns, then just return them and try a different pair.
Hope that helps some. I think it is highly unlikely you will get treated badly. The fitter I had may not have been bad at all. I should not have asked them to make an adjustment at my direction. She was not the type that took direction well from somebody she did not know. And that is another point, the relationship with the fitter is important. If you have a personality clash and don’t communicate well, then ask for another fitter. The manager of the department tends to be the most experienced one there. Ask for the manger.
Hope that helps some,