Yes, that's how I do it. At boot a service auto-logins on all vts and fires up an X server with my WM. Since I already have to enter a password to decrypt the disk this is OK. After half an hour idle/suspend the screen gets locked, so it's not worse than no auto-login.
Sadly, the documentation and wiki has detoriated in quality the last few years. For example I recently tried to look up how to run Xorg without suid, but the wiki had removed the simpler input-group based method in favor of this elogind stuff, which I consider to be worse than useless. Luckily the talk page pointed me in the right direction (history).
Personally, I put -* in make.conf's USE variable and only enable a few things I really want universally like threads, unicode, etc. Then I use flaggie to enable the flags I need when installing stuff. I check with emerge -a to get a list of everything with the possible flags, then enable/disable as necessary. Takes a bit longer the first time, but prevents stuff like this. Sometimes it can break stuff since that's not a supported configuration and might expose undeclared USE flag dependencies, but it's mostly OK.