"The truth is that all of this crucial basic info should be told to you by your specialist. If they didn't advice your properly, choose another one."
Oh, great, so newcomers to CIEMs should wait until told by their CIEM vendor that their impressions are substandard and then "choose another" audiologist? Wonderful.
Your idealism is admirable, but your presumptuousness is, dare I say it, 'questionable'.
This thread was not, as you condescendingly put it, contributed to by "those who are afraid of audiologists and hence want to read 'ahead' ". It was contributed to by head-fiers who have either been stung by paying for impressions that turned out to be sub-standard or inappropriate for CIEM production (even though the impressions might, perhaps, have been appropriate for hearing-aid production), or who wish to forewarn other newcomers to CIEMs to be very specific in how they approach the process. The requirements for impressions for the purposes of manufacturing CIEMs differ from those intended for hearing-aid manufacturing. There is, of course, a good deal of overlap, but outside of that overlap, are important factors which many audiologists are blissfully unware of.
Since your remarks appear to imply that you have experience in this area, I am left to wonder whether you were simply fortunate in finding an audiologist already well-versed in the specific requirements for CIEM impression-taking, have abundant time and funds to waste on 'choosing another one' (audiologist), or are, perhaps, simply being obtuse for the sake of your own amusement, or if you actually have no experience whatsoever. I will give you the benefit of the doubt and assume that you, perhaps, fall into one of the first 2 categories, or similar. You were ambiguous, in your use of the term 'specialist', as to whether you meant the audiologist or the CIEM vendor. In either case, I can personally attest that when I presented the printed instructions from UM (which are broadly similar to those provided by JH Audio and many other CIEM vendors), my first audiologist just laughed and said he'd been taking impressions for hearing-aid users for 30 years and that the UM instructions were pedantic. The result? Ear impressions lacking in definition in the region of the crus of helix, and wasted time and money having to have them redone.
Not all CIEM newcomers were taught, as part of their school education, the specific requirements for taking ear impressions for the purposes of CIEM manufacture. So how are they to know if the audiologist they approach really knows the specifics?
Not all audiologists were taught, during their professional training, the differences in requirements for taking ear impressions for hearing aids vs. those for CIEMs, but many will nonetheless casually bluff their way forward when asked by potential customers if they know how to take impressions for CIEMs. This can result in a potentially expensive and time-wasting experience for the CIEM newcomer, and none of us enjoys that kind of scenario. It is not easy for first-timers to be able to have the necessary understanding, certainty, and fortitude to override the arrogance of a time-served audiologist who may know less about CIEM specifics than they presume to know.