On wearing the M&RIE receivers, if you wear a very occlusive mold, you might fall into the camp of those folks with moderate to severe gently sloping loss that ReSound tags as suitable. The other camp are those folks with mild to moderate gently sloping loss.
Here are some figures I posted from a ReSound Audiology Online course I took in September 2021. See the third set of fits with the “Good Fit Candidate” in the graph on the right. That is approximately your loss. The other rule (last set of figures in the referenced link) is that your prescribed gain cannot intrude more than 10 dB into the feedback regions (the ballooning pink regions descending from the upper part of the graph).
If you look at my fit, by the ReSound course graphs, I should not be able to wear the M&RIE receivers successfully. I have a very mild loss at low frequencies that quickly becomes moderately severe at high frequencies. Yet my molds fit so well that very little sound produced by the receivers escapes my ears, and even with far more high-frequency amplification than the ReSound Audiogram+ fitting algorithm would prescribe, my prescribed NAL-NL2 gains do not intrude at all into the minimal feedback regions I have with my molds. Costco may have a more economy-minded fitting policy. My audi was willing to let me try M&RIE receivers with her loaners (I did pay her to have custom molds made), and since the custom molds worked for me, I got the M&RIE receivers with the Omnias I purchased. When I didn’t like the length of the wires, she let me switch out the receivers to a longer length wire at no charge.
It’s best to go with what you and your HCP are most comfortable with and like best. But custom molds at Costco are relatively inexpensive. It might only cost you $100 for a set of molds at Costco if your HCP had a loaner set of M&RIE receivers to let you try. On Dr. Cliff, AUD’s YouTube channel, he’s said that most of his patients who’ve tried the M&RIE receivers prefer them over standard receivers. A number of users on this forum who’ve tried the M&RIE receivers have reported feedback issues, but that may be in part a function of how well the impressions were taken and how well the molds were made.
I think the most important thing is to decide whether the Phillips 9040s or the Enhance Pro 10s are more to your liking with the loaners Costco is providing. If the 9040s work better for you, the M&RIE receivers are a moot question. But if you decide you like the Enhance Pro 10s the most and don’t mind possibly wasting ~$100 on custom molds, you might try relating the info in the graphs to your HCP and see if he is willing to let you give them a try. Sorry if I seem to be overselling the M&RIE receivers. I really like mine and I’m glad I took the gamble to try them.