Change the update program so it:
Asks for root privileges([gk]sudo or whatever) when actually making changes to non user-specific files.
Keeps privileges intact for all files.

This will:
Make updating as easy as with the windows client.
Make it easier to make distribution specific packages.
Make it possible to use safe permissions.
example:
owner:root = read, write, execute/traverse folder
group:users = read, execute/traverse folder
other = no permissions

(group could also be tsusers(for example) for extra security)

As it works now:
Update uses current user when making changes to non user-specific files(Will fail if safe privileges is used and owner is not current).
Update overwrites permissions.

Workarounds:
Install TS3 in your home dir;
Use unsafe permissions(g=rwx for example) when installing in /opt (or other paths);
Start Teamspeak as root then press update.

Results of workarounds:
Bad Security.
Bad multiuser support.
Bad distribution compatibility.
Complicated update.