[Exim] Safe, reliable use of exim -C?

A couple of weeks back there was a discussion involvind using "exim -C
<file>" and Philip chimed in with some thoughts on when that would not
work reliably.

I have a new server to set up, and it will be running a few (4-5
initially) separate instances of Exim, with separate config files. In
order to avoid having to keep multiple copies of the Exim binary around,
I was planning on using -C when I started each daemon to point to the
proper configuration file.

In this case, these Exim daemons will never do any local delivery (there
are no local users), and all remote deliveries will be over TCP sockets
(SMTP or LMTP). There will be lookups against a MySQL database using a
Unix-domain socket. As best I can tell, in this environment Exim is
never going to have to "regain" root privilege once it has given it up,
so I should be safe using -C to point to my config files.

However, I'm open to being told what I've missed :-)