Back out plan for Forest Functional Level upgrade.

Hi All,

I know - nobody is in the world haven't had problems with functional level upgrade before but I have to have back out plan, so =)

Environment:

Single domain forest, two DCs running 2k3 SP2 as virtual machines.

Windows 2000 forest level, windows 2000 native domain level.

Goal is to upgrade forest level to 2003 level.

Plan:

1.    Shutdown DC02
2.    Make snapshot of DC02
3.    Shutdown DC01
4.    Switch on DC02
5.    Raise Forest level on DC02
6.    Check If everything is fine. If not - go to Back out process.
7.    Switch on DC01.

Back out process:

1.    Revert to snapshot DC02
2.    Switch on DC01

I know it is not recommended to use snapshots for backup of DCs, but as we have tiny environment with only two DCs and one will be powered off, I don't see how it can make USN rollback or any other issues.

All concerns and recommendations are very welcome.