I tried a multi-boot with Ubuntu jaunty, Mint 6 main, Mint 6 XFCE, and PCLOS 2009.1 KDE. PCLOS' installer insisted on installing its first partition as a primary partition. This kept closing the extended partition I had set up to handle all the partitions needed to run 4 OS. I finally had to install PCLOS first and let it set up the primary partition for swap. Then I could open an extended partition for all the other distros.
Then once I had everything set up and working well, I made the mistake of updating PCLOS. Somehow, the updates killed my multi-boot grub menu and the only OS I could boot to was PCLOS.
As Husse said,
BUT lots of distros are not as nice to other installed systems as the Mint installer
When you install PCLOS, keep a watchful eye on it.