How compatible are RHEL and clones?

[Chris St. Pierre]

We're looking at installing a pair of boxes to do LDAP in a
load-balanced environment, and I was considering putting RHEL on one
with the corresponding license, support, etc., and then putting
CentOS, White Box Linux, etc., on the other and keeping the config
files, software, and everything else synchronized across the two in
order to save money on the RH license.

1.  Is this even possible?

2.  Is it a good idea, or out-and-out stupidity?

3.  Has anyone else done this?

4.  Are any of the RHEL clones any better than any of the others as
    far as compatibility is concerned?

Thanks!

Chris St. Pierre
Unix Systems Administrator
Nebraska Wesleyan University