Very nice machine. I have MorphOS, MacOSX and Debian Sid here.
You can use at least these recent linuxes: DebianSid, fienix (http://fienixppc.blogspot.com/), MintPPC (http://mintppc.nl/)
I started installation with MacOSX and other systems later. After installation of OSX use only one disktool (or gparted or hdconfig ) mixing of these tools can result in incorrect partition sizes. If you brave enough, you can prepare all partitions with OSX diskutil only.
The simplest way of triple boot selection is powermac graphical early startup(alt). The second is edit grub config (or yaboot config if you use it)
I remember that the latest debian Sid install image not works, you have to use older - I look at home which version works with grub nearly out of the box (the only thing which you have to do manually is to bless grub - after this it is visible on early startup.
Is Your graphics card X1950 PC flashed? If yes, it can work for all OSes. If you have original X1900 G5 edition, it doesn't work with linux (no accel). In this case you can use second card (HD6670 is one of the best 1slot with accel) and make custom xorg.conf. I can send it if you are interested.
Web browser I use Arctic fox from repo.powerprogress.org
And about Chrisalis - it is very nice collection, I cannot see any bug, but me personally install only parts of it, not whole Chrysalis pack.
AmigaOS: Micro A1-C, AmigaOne XE, Pegasos II, Sam440ep, Sam440ep-flex, AmigaOneX1000
MorphOS: Efika 5200b, Pegasos I, Pegasos II, Powerbook G4, Mac Mini, iMac G5, Powermac G5 Quad