Can I move these items around in active directory

Can I move these items around in active directory

I am just reorganising my companies active directory structure, as it
hasn't kept up with changes in the company structure.
There are a few items I am not sure if I can move or not. Can anyone tell
if it is ok to move the below or not:
Exchange Security Groups OU (Exchange 2010)
Exchange 2010 DiscoverySearchMailbox user account
Exchange 2010 SystemMailbox (x2) user account
Builtin groups found in the Builtin container
All builtin accounts/groups in the default "Users" OU
From what I have heard, the Exchange Security Groups OU can be moved in
it's entirety as it has a well known GUID and Distinguished name. I am not
so sure about the accounts for system mailboxes, although I can't think of
any reason why not. All the builtin accounts I assume are fine to move.
Obviously the above statements are only true if they were to be moved to
an OU without weird GPOs.