what distry are you running?
on windows it runs 100% in parallel to your old sauer.
on linux i've no idea (depends on how you install it and where you extract the files, if you place all the files expect your binary in a specific supersauer-folder and link to it via the home-folder command youre save)
and on mac you are correct youre settings will be reused (but you still can play both in parallel just with 2 different apps)

Using Windows7, basically SGT Ross model wasn't displaying, my playermodel skins weren't reverting after playing round in-game and my custom hudguns for Snout & Fixit were just floating hudhands. The latter might have something to do with a different directory, I assume that SuperSauer searches for the default Collect directories?

I'll do some more fiddling around to see if there's anything else not loading alongside.
Bugs:
Sound Settings (music was muted before)
Custom Crosshairs (not loading)
Autoexec.cfg (not loading)
Saved Custom Maps (it looks like your mod isn't also looking under C:\Users\[name]\Documents\My Games\Sauerbraten\, that might be the main issue as Windows Sauer saves custom content there. Plus I use that directory a lot for custom content as it's easier to access for me)
Resolution was higher than Collect's initial default setup, also the window was bigger (I don't play fullscreen)
Framerate is seriously low (2fps!) on my largest map (not released) with this mod. Without mod I can get around 15fps viewing through wireframe.
До свидания и заткнись
-P

Thats actually not a bug, thats a feature.
Its saving any configs and new content into "my games/supersauer", instead of "my games/sauerbraten".
If you want to play with your old config, you can copy the files you want from the old directory into the new one.

I think this will also solve the fps-mystery, tell me if not.

That's fine for saving new content but it's not looking for old custom content under C:\Users\[name]\Documents\My Games\Sauerbraten\
До свидания и заткнись
-P

Install your old custom files once again and you're good to go.

Lagometer explanation:
Lagometer

Lagometer with examples:
Interpeting the lagometer, rate, fps, snaps, etc

Their snapshots seems to be interpreted as our packetjumps.

An example for the speedometer (as a vid borrowed from youtube):
Speedometer (from 0:03 - 0:15; on the rest of the vid the graph doesn't change due the range limit of about 1000 units/second)
Look at the right of the screen.
The variable parameter obviously means the current speed of movement while the graph visualizes it. The graph is more often useful to see how fast you were going in the past.

SHADERS ... MMMHAHAWWWWHAHAHAA

How can I fix it?

try reinstalling glsl.cfg :)

No, that didnt work either :/

I created a little Faq-Page :)
http://supersauer.blogspot.de/p/faq.html

the point "i have texture errors on windows 8" should do the job.
just copy all files of "my documents/my games/supersauer" into the sauerbraten-folder directly.

Didnt seem to work :\ I am running 32-bit windows 7 pro.

hm okay, this should actually work in any case ..
soo:

1. install sauerbraten somewhere (maybe try to install it into your user-account, e.g. "Desktop/Sauerbraten")
2. install the supersauer-mod via the provided supersetup..exe
2b. as path you specify this program path above.
3. if its not working already then, copy all files and folders from "my games/my documents/supersauer" into "Desktop/Sauerbraten".
4. to start the game click the desktop link (or if its not working the file "Desktop/Sauerbraten/supersauer.bat")

That didnt work :( Are there any minimum specifications?

nope, there are no minimum requirements other than what sauers requires.
if you want i can help you over teamviewer installing it. I wrote you a pm

Will take a look in my archive soon.

The author should still be active by the way.

Yes I am, however I abandoned this mod (links are reupped though on https://github.com/a-teammate/supersauer/releases/tag/1.0.1 )

Thanks! :)