I decided to share my experience. I got my Pangolin almost a year ago and it came with Ubuntu 8.10. I feel Gnome is getting outdated, so I decided to switch to KDE (after having used it on my desktop). I know that system76 doesn't officially support KDE, but I decided to post this anyway:
Sound, Video, 3D Video, Keyboard + Shortcuts, Touchpad + USB Mouse all work.
Camera and Mic also work for Skype.
WiFi and Wired network both work. KDE Network Manager can use some work, but does the job fine enough.
Kwin 3D cube is a bit more jittery (when switching desktops), then Gnome + Compiz, but this might be because of the different wallpapers on each desktop. It just doesn't cash them all in memory. I will see if I can fix that.
Virtual Box + USB support works (I had to add myself to the ld group for printing, but this was minor VB issue). Tested it with Windows guest only.
Suspend and Hibernate work, however, more testing is needed to see if stability will suffer if we use too many suspend-resume cycles.
I installed the System76 driver, however, everything seemed to be working without it anyway. I am not sure if it actually provides any drivers for my specific laptop or is it just a log creating tool.
I observed the AC power bug. The laptop doesn't recognize when the AC cord is plugged and doesn't switch to performance mod. Luckily KDE has a nice widget so that I can manually control this with couple of clicks. Battery level is measured, but battery time is not. I posted on one of the other treads. I will try to recompile the kernel to see if it will have an effect.
Another odd bug is that upon boot, sometimes the log in menu will not appear. Or it will appear for a split second and then the splash screen will show up. I have never observed this on my non Sys76 desktop. Ctr+alt+F1, then killall Xorg, then startx fixes the issue. I will see if the splash screen settings would prevent it from happening. The bug random, so testing is not very easy.
I have not tested the fingerprint reader, I just don't use it.