I have servers in both config's and both work well with out problem

contribs server is good enough with updates, the firewall is great. I only use IPCOP when Contribs is being used as a file server that must be real secure. Then the extra hop to the outside world is better. I don't DMZ, only open and forward the ports you need, normally 22 for SSH / some times PPTP. But if only for admin work just SSH, your can tunnel the rest through your SSH session EG server-manager, etc.
