After more tinkering, I've decided to leave the phone on production build .420. Iris scanning is noticeably faster on this build.
The phone does not get hot (it gets comfortably warm), though it certainly heats up on some tasks I'd consider less-than taxing. Of course, I'm certain this is part of W10Ms teething process. Ordered one of those knockoff cyan back covers, so that'll arrive whenever it gets here.
Love the phone so far and all it has to offer. Camera, especially, is fantastic. I do notice that when I have auto HDR on, it more often than not decides that the scene NEEDS HDR. Pictures come out fantistic and there's little slowdown but I still find it interesting that the Lumias are liberal with auto HDR, just as they're VERY liberal with auto flash
Battery drain is... average. By no means is it appalling, but it's nowhere near as low as my 1520's discharge rate, nor my iPhone 6s. Again, I attribute this to the teething process.
Again, so far, so great!