Well, if your Costco fitter thinks power domes or double domes would work to control feedback for you and they have loaner M&RIE receivers, I’d suggest trying those with your loaner Jabra Enhance Pro 10s. I have the ReSound Omnia 962s with size 13 disposable batteries (day 11 on my 1st set, and I’m still going strong!). I really like the sound with M&RIE receivers. Perhaps how much you’ll like the Jabras depends on whether you’re an iPhone (and Apple Watch) user. ReSound does not lie when they say hands-free phone calls on the iPhone are crystal-clear (I found the sound of phone calls better than with the Lumity 90-R, which I trialed, but then I only took a few Wi-Fi network phone calls with the Lumity, so perhaps not a fair trial). Whether calling with my Wi-Fi network or with Verizon cellular (the provider for the MVNO Spectrum Mobile), the calls sound great, and my callers agree.
Lumity users are saying, “Oh, the battery life isn’t an issue,” or “Oh, I never need to use my app,” but I found both of those items annoying with the Lumity. I didn’t like always reverting to the automatic program, either. Perhaps I lead a much more active, yardwork-, housework-oriented life than most Phonak users! I really enjoy having ~the full ReSound Smart 3D app on my Apple Watch Ultra. The app is extremely responsive on the watch and saves pulling out my phone. Too much noise, I can quickly turn the volume on my mics down or shut off my HA’s entirely. Switch to the Music program? Just a few taps on the watch calls up the Music program, no playing with buttons behind my ear, etc. Same for adjusting relative streaming/external mic balance. So handy to have control on a watch always on my wrist versus the “where’d my phone go?” option.
With the Roger On In, the Lumitys should be great and certainly worth putting up with less than ideal battery runtime, especially when streaming a lot, and putting up with an app that Phonak ought to improve to match their excellent HA’s. Especially with your hearing loss, I might think the fairest trial (hardly worth it, though) of the Jabras would be with custom molds. That’s what I have for my M&RIE receivers.
Edit_Update: If you want to trial a sound equivalent to mine with the Omnias, you should ask your fitter to set you up with an “Experienced User Nonlinear” user profile and use the NAL-NL2 fitting algorithm. You seem to have a cookie bite loss, whereas I have a more usual, age-related high-frequency ski slope loss. So perhaps the NAl-NL2 fitting algorithm wouldn’t do as much for you as it does for my high-frequency hearing problems.