Plans to upgrade Enterprise Vault from 9 (32bit) to 10 (64-bit)

We are currently running EV and DA in the following configuration:

Single EV site

2 EV MailArchive Servers (Windows 2003 Std SP2 32-bit, EV 9.0.5)

1 EV MailJournal Server (Windows 2003  Std SP2 32-bit, EV 9.0.5)

1 DA Server  (Windows 2003 Std SP2 32-bit, EV 9.0.5)

We need to upgrade to EV 10 to support Exchange 2013.  What has thrown a wrench in the clockworks is that there is no migration path from DA 9.0.5 to DA 10.  Only from DA 9.0.5 to DA 11.

I know that DA11 would be compatible with EV10, but from what I've read, DA11 requires the EV10 binaries installed.

So the question is, will the DA11 server with EV10 binaries work in the environment until we upgrade the EV9 servers to EV10?

Has anyone done the upgrade from DA 9.0.5 to DA 11?