ZxBackup zimbra OSE 8.8.8 multi server enviroment

Hi!

I have one massive zimbra server with ~3000 mailbox. The server cant handle really well the high load. So i decided to split up into multiple server. This is an already working enviroment.
- LDAP only
- Mailbox (store, pop, imap, webmail, webadmin)
- MTA (antispam, antivirus, smtp)

I need to export from the old and need to import to the new. The old server also 8.8.8 but upgraded started from version 6.x.x and it was ubuntu based. I just upgraded every time and then change to centos, so its really need to migrate everything into a clean install.

I see the zxbackup currently not supported zimbra 8.8.8. The zextras suite trial version do the job for me?
Also in what server need to install the zextras tool from the 3 above?

Thanks for the help!