Simple question.

If you try to install the iprint client for Linux you get several
unresolved dependencies regarding cups and I am hesitant to install
cups on an iprint server because I am pretty sure this would screw
things up.

But if your iprint printers require authentication, you cannot use
these printers locally as without client there is no means of
authentication for print jobs. Neither lpr nor printing from an
application does work.
lpr does ask for a password but fails regardless of the password
entered, if printing from an application this silently fails.
W. Prindl