I think the issue is that none of the DU devs own a Marlin anymore...so they can't support it. Also I don't think they are a fan of the A/B partitioning either (But they are developing for the Pixel 2.... so maybe that's not it). I'm also pretty bummed, and thought about rolling back from 8.1.0 to 7.1.2 and running an older DU build, but figured it's more important to stay current with security updates. I'm currently running Stock Oreo 8.1.0 with the January security patch and have Magisk enabled for a few apps. Will probably flash the February patch in the next few days and re-root with Magisk again. It's really stable, and I was able to theme it with Substratum, I use Nova launcher, and have most of the functionality that I get with a custom ROM with stock, so not totally dissapointed.