I figured it might create ever bigger problems (from an admin point of view, not the os) to mix the filsystems.
Why? Filesystems are distintively separate modules. The Virtual Filesystem (VFS) subsystem ensures part of that too.
That other admins might try to force fsck.reiserfs on a ext3 partition for instance (or even worse things for that matter).
There ARE other admins in the world but us you know. ;)
Regards, Harald