I do something similar with Sanoid/Syncoid and Sanoid snapshots are super easy to hook into with Borgmatic so you can have an alternate backup set that has nothing to do with ZFS.
The very first system I ever installed ZFS on had a consumer grade motherboard and very soon after installation I realized one of the SATA ports would get flaky under load because ZFS kept spitting up errors. The controller didn't report errors and happily wrote garbage to the disk from what I could tell. So, IMO, checksumming isn't worthless and I keep all my important data on ZFS these days.
I also disagree with the layering thing. I know it's the "unix way", but chaining together a half dozen independent system isn't something I find appealing. At that point I'm the biggest risk to my own data because the odds of me making a mistake are higher than the odds of hitting a bug that affects data integrity. I'd much rather have a single coherent interface to deal with.
It was the same thing with SystemD. Everyone complained about it "taking over everything" instead of chaining a bunch of existing uncoordinated systems together, but I can't imagine going back to the old way now that I'm used to SystemD. It would be nice to see a SystemD style initiative for desktop Linux.