So, I hate threads like this that donāt have a resolution, so I wanted to report back, especially to those who took the time to share your knowledge with me.
I tried to order the IDMAX15, but no one had it in stock. I called Image Dynamics directly, and they said it may take a month or more to get in a certain part that is back ordered so they can build more drivers. But even then there was no guarantee I would be able to snag one.
So, I got a Adire Brahma instead. It was the last of the previous model (the 2018-2022 MK 2.5, not the rev A) they had in stock, so I got it for a good price.
I installed it today, and I gotta say, even with a box that is not ideal for it (Andrew from Adire says the port area is too small) and even though it isnāt broken in yet, it sounds so much better than my last sub.
It extends lower (a very noticeable difference on Hip Hop and Reggae, less of a difference on rock/metal and other genres I listen to, but still a cleaner, more even sound) and is super low distortion.
With my previous sub, I never realized that my stock speakers were also getting bass frequencies (duh, they are not crossed over or capped). But with the Brahma, the full range speakers also trying to hit bass notes sound very dirty, because the Brahma does those same notes without distortion. I had to order some capacitors to roll off the base on my main speakers so they leave the low end to the Brahma.
Overall, I am very satisfied with the Brahma 15, and may eventually get a box that is made specifically for it.
Thanks for all the advice!