Not sure if this helps any. We had a small domain here with 6 physical servers, of which 2 were DCs. The PDC was running Windows Server 2003 64-bit and the secondary DC was running Windows Server 2003 32-bit.
We converted 4 servers P2V. One of the machines we converted was the secondary DC (the 64-bit PDC has remained, for the time being, a physical server).
We didn't experience any problems with the P2V of the DC. We ran the Converter program, shut down the old physical DC, then booted up the virtual and it all just seemed to work. Didn't notice any replication errors in the logs.
The domain has been running quite reliably since then with the PDC as a physical server and the secondary DC as a VM guest.
EDIT: we will run like this for a few more months, then plan the migration of the remaining PDC. Unfortunately that machine is also an Exchange server, so I will need migrate all the Exchange stuff off it first.