The biggest problem is the saturday of registration each quarter. It nearly melted down last quarter, but they think they can use the same hardware and move things to mod_perl for this quarter.
As a test, they took a mod_perl server, and just with Apache::PerlRun (which recompiles the code on each hit, but doesn't fork), they were able to easily improve on a custom C program in CGI mode, talking to a database and executing a simple query. A short Perl program replaced the much-more-clumsy C program.
They're sold! Just wait until they discover Apache::Registry and points beyond.
Just today, I got a complicated version of their Apache server to compile in DSO mode (except for a weird mod_auth_dce module), and demonstrate a caching reverse-proxy server using their existing CGI base, so they have a migration path for mod_perl. Joy.