Thanks to all who gave helpful suggestions about running VMs in Gentoo. The main reason I wanted a VM was to play around with some other distros and see what I liked.
But then I got to thinking, and I realized that I have over 250 GB of free hard drive space sitting around. So I made a new little partition and per Noah's suggestion, threw Arch Linux on there.
I'm fairly impressed so far. The install was easy. In contrast to the enormous Gentoo handbook, the whole Arch install guide fits on one page of the official Arch wiki. Why doesn't Gentoo have an official wiki? I know there are concerns over the quality of something anyone can edit, but in practice is it a big a deal? Is it worth the price of sending users elsewhere, to potentially even WORSE places, when the Gentoo docs don't cover everything we need? The quality of the unofficial Gentoo wiki is often very good but sometimes hit-or-miss, and it also sort of crashes and loses all data without backups every once in a while.
The Arch installer is a commandline app using ncurses for basic menus and such, which is more than sufficient and a good compromise between commandline-only and full-blown X-run Gnome bloat. The install itself went fine, other than my own mistakes. I'm sharing
/home between Gentoo and Arch so I can switch between them easily. During the install Arch tried to create some GRUB files, but they already existed care of Gentoo, so the install bombed without much notification and I didn't notice until 3 steps later. No big deal to fix, but I'd have liked a louder error message right away when it happened. The base install took about 45 minutes.
Another nice thing is that the Arch install CD has
vi on it. I didn't have to resort to freaking
nano or remember to install
vim first thing. A mild annoyance to be sure, but it bugged me every time I installed Gentoo.
After boot, installing apps via
pacman is simple enough. KDE 4.2 installed in about 15 minutes, as you'd expect from a distro with binary packages. I found a mirror with 1.5 Mb/sec downloads, which is awfully nice. Syncing the package tree takes less than 2 seconds, which is also nice compared to Portage's 5-minute rsync and
eix update times. Searching the tree via regex is also somehow instantaneous in Arch.
Oddly, KDE didn't seem to pull in Xorg as a dependency, but other dependencies worked fine so far. Time will tell how well this all holds up. Most package managers do fine on the normal cases but the real test is the funky little obscure apps.
pacman -S gvim resulted in a Vim with working
perldo, which means Arch passed the Ubuntu stink test.
Another nice thing is that KDE4 actually works. My Gentoo install is years old and possibly crufted beyond repair, or something else was wrong, but I have yet to get KDE4 working in Gentoo without massive breakage. Possibly if I wiped Gentoo and tried KDE4 without legacy KDE3 stuff everywhere it'd also be smooth.
Regardless, it all works in Arch. NVidia drivers and Twinview settings were copy/pasted from Gentoo, and compositing all works fine. No performance problems in KDE with resizing or dragging windows, no Plasma crashes (yet), no missing icons or invisible notification area. QtCurve works in Qt3, Qt4 and GTK just fine. My sound card worked without any manual configuration at all. My mouse worked without tweaking, including the thumb buttons. Same with networking, the install prompted me for my IP and gateway etc. and then it worked, no effort.
I've mentioned before, but one nice thing about Linux is that if you have
/home in its own partition, it's no big deal at all to share it between distros. With no effort at all I'm now using all my old files and settings in Arch, and I can switch back and forth between this and Gentoo without any troubles.
So we'll see how this goes. So far so good though. Arch seems very streamlined and its goal is minimalism, which is nice. Gentoo has not felt minimalistic to me in a while. Again, may be due to the age of my install, cruft and bit-rot.