I feel that going from 8W to 3W, while gaining a more usable system that also sits on ZFS instead of ext4, is more than enough reason.

ext4 doesn't detect corruption. How am I supposed to trust it?

And corruption actually happens.

My Dell has an Sk Hynix NVMe drive that apparently doesn't have safe write on power failure. I know because it somehow woke up in my bag and ran the laptop battery down to 0.

BTRFS was not happy with the state of anything on the drive. I was able to do a rescue copy and verify it with my backups, so after a full restore everything turned out OK.

It seems like a good deal but what about the support and the upgrade path from Dell?

I get what you're saying about the filesystem. Personally, I use par2 for the most important things (photos).

What about it? It doesn't seem to be enormously useful, given I can do so much better on my own.

I got the laptop to have well-supported hardware, not because I was expecting a lot of help from Dell.

Is that all there is to it, just well supported hardware? Dell didn't configure Redhat in any way, to make better use of the hardware? I'm thinking trackpad, sleep and hibernation, graphics etc.?

Ubuntu, not Redhat.

And no, it seems they didn't. They haven't forced deep sleep, for example.

Thanks, very interesting to know about these little shortcomings, and how you solved them.