Environment = Windows 2003 native domain with 8 DCs

I've got an old domain controller that is running 2003, CA Enterprise role, DHCP, DNS, a few GPO scripts that point to shares on it, and some other minor functions. All our servers point to it as their primary DNS, and there's lots of references to its IP or name throughout the domain at this point (8+ years later). I really don't feel like manually changing all of this, it would be a pretty massive undertaking.

I want to follow this guide: http://msmvps.com/blogs/acefekay/archive/2010/10/09/remove-an-old-dc-and-introduce-a-new-dc-with-the-same-name-and-ip-address.aspx to hopefully end up with basically an "in-place upgrade" so to say.

I considered just doing a P2V of the box, but we don't really want to keep it around running 2003 to be honest. I also considered using a CNAME and adding a 2nd IP (the old one) but again, it seemed like it would be cleaner using the attached link.

My actual question:

Any gotchas or big caution signs when doing what the link suggests? Anyone gone down this road and have advice on how to proceed?