[Quoth]

I've had maybe 9 makes of dedicated ereader, and three models that were LCD (really). iRiver Story Cover, Binatone, Amazon, Kobo, Sony (2), Nook, reMarkable, Boyue and yiben Y-Ben P47L.

I've used maybe 8 models of Kindle (some borrowed and I still have 3).
I've used or owned maybe 7 models of Kobo. Bought 3 Sages as presents for others.
I have an Elipsa and because of it bought the Sage for ereader and note taking. The 7.8″ boyue Mars* isn't bad as an ereader with Android, but Sage or Libra (or Libra 2) are all far far better for epub.

I have the Libra and Libra 2 (both far than 32G 3G/4G Kindle Oasis I gave away). But I think even if you don't buy the Pen and use the Sage only for ereader, it's the best dedicated reader ever. Very fast and the current crop feature makes it good for PDFs. I've used Kobo pen and an almost identical 3rd party pen for MS Surface. Still on first AAAA cell on Sage and Elipsa.

[* Now sold as Meebook P78, plus it does run Kindle, Kobo, Bolinda Borrowbox, Google PlayBooks & KOReader, cons: no page buttons and no decent library like Kobo/Kindle and pig slow with Calibre (because it's USB MTP). You can disable entire Google with one click. Runs K9 email, LiChess and audio (3.5mm jack or BT), but unless you need Bolinda for Irish Libraries, Android is pointless for an ereader]

I've replaced the cell (AKA battery) in a DXG, 2x KK3, a Kobo H2O and several phones. Can battery be replaced in the Forma?