Portupgrade on In Use Perl Install -- How bad an idea is this?

So I've got a FreeBSD box that I serve webpages from. It has Apache, Perl, and MySQL primarily doing web stuff.

I've been reading up on "portupgrade" and it seems like a nice way to stay up-to-date on various ports. Plus, I'm having trouble installing Apache-MP3 (to stream mp3s), and it appears that it may be due to my having an older version of mod_perl, but the newer version requires Perl 5.8.

If I run portupgrade to upgrade my Perl install which is currently at 5.00503 to 5.8, will my apps still work? Will they point to perl in the right place (/usr/bin/perl)? Does "portupgrade" just upgrade files as opposed to creating a completely new install?

Thanks......Doug