I'll take a shot at this.
When you move a client from one domain to another:

1) No data moves.  Even if the backup copy groups in the new domain point to
different storage pools, the existing backup data stays right where it is
(and is still perfectly restore-able).  If you want to move the data, you
have to issue the appropriate MOVE DATA or MOVE NODEDATA commands to make
that happen.

2) If the new domain has management classes with the SAME NAMES as the old
domain, the data will be governed by verexist/verdeleted/retextra/retonly
values in the new domain.

3) If there are management classes in the old domain that DO NOT EXIST in
the new domain, the data is governed by the "backup retehtion grace period "
value for the DOMAIN.

Also in this case some ugly messes crop up.  When expiration runs, you will
see a LOT of funky error messages about backup copy groups not existing for
file xxxxxxxxxx, which essentially says that there is no management class.

Wanda Prather
"I/O, I/O, It's all about I/O"  -(me)