1) It's good to know that the missing USE flags are being addressed.
2) As to make.conf, I'll probably reorganize mine and compare yours to see what I can add/change
3) As to masking vs continuous change, again, it would be nice to have a single thread with a "mask this to fix that", or an unchanging url in the wiki
Sabayon may be a month or two behind, but does the overlay allow for a new package.mask,.use,.unmask? It took a while to realize that there were at least two package.mask files to worry about: in /usr/portage/profiles and /etc/portage.
And, why can't Sabayon add by default the lines:
"PORTAGE_ELOG_CLASSES="info warn error log"
PORTAGE_ELOG_SYSTEM="save"
to make.conf and maybe run mirrorselect on first boot (or, at least give the option).
And, being a user of QEMU, maybe add GCC 3.4.6* to build it (or make it an option like nfs of 3dgames).
Just trying to improve the user experience and streamline things.