@mikewalsh The E1 iso in post 1 is the most recent version. At some point in the development deltas were dropped as being confusing. I've been running E1 albeit customized with PCManFM, my symlinks and JWM configuration, and synaptics drivers for touchpad in a ydrv for some time now and other than adjusting for my quirks and helping troubleshoot an ad-blocker issue for ozsouth I can't point to any issues. Have a go with E1.
OOTB it comes with an overlayfs only kernel but will run happily either with overlayfs or AUFS file systems with any of the 'usrmerge' recent kernels that support AUFS and ovelayfs (like @ozsouths' 6.1.23). Bear in mind that the savefile structure is different for the two FS.
I'm currently running it overlayfs as intended with peebees 6.3.0 kernel with the structure adjusted for usrmerge by @jrbs' script zdrv_cp2deb
in the boot directory and punionfs=overlay in the boot stanza. jrb is running ozsouths 6.2.9, see here: viewtopic.php?p=87366#p87366.
FWIW, Bookworm Pup64 runs swimmingly with the same packaging. A couple of multimedia hiccups there that will get ironed out with the next release but it shows @radkys' polish. jammypup64 is more of a 'core' system, while Bookworm is quite full bodied. I like both for different reasons.
an inveterate tinker 