Anything special you did for the Gentoo install? Maybe do a quick writeup of what you did and your experiences?
I'm a Gentoo user on my other boxes, and obviously thought about it on the Novena. Not sure about the build times or problems getting set up, though. All the stage 3 tarballs I've seen are pretty old for ARM.
Slightly off-topic, but I'll just answer here.
No, nothing special, but I ditched it again in favor of the regular Debian. It was just too painful to compile Webkit for >12 hours on the Novena and things like gnuradio failed with obscure X11-errors. I was fed up in the end
If you _really_ want to use Gentoo, you absolutely need to distribute the load with distcc.
For the setup itself, getting the boot environment right was the hardest part. Especially because I wanted an encrypted root partition. I mostly did it like the novena-image.sh with encryption support here: https://github.com/jogi91/novena-image.git
The u-boot environment, the disk signature and the sata-boot flag in the eeprom are the things to be aware of. In the end I grepped through the novena-u-boot sources to understand the disk-signature thing (see: hxxps://github.com/xobs/u-boot-novena/blob/novena-r2/board/kosagi/novena/novena.c#L369).
I still have a lengthy (>200 lines) textfile with all my notes, but it was mostly following the manuals and adding things here and there to make it boot on the Novena.