Move an account from 2 servers

Hi,

First of all sorry for my bad english writing, its not my first language ... And im writing you this msg with my iphone its doesnt help

I need to move a urge account 30 GB from a shared server to a dedicated one ...

If im not wrong the cpanel procedure :

- backup account
-copy tar file to new server
- restore backup

Will take a long time +/- 6 hours and the problem is the owner of this account want a short downtime like all client but this one is a major league.

What is the best procedure to move a urge account like that with a minimum of downtime ?

I was thinking to do the cpanel procedure but rename the domain to domain-new.com and when we are ok to move only rsync the difference beteeen both account and rename the domain to the old one and give him back his ip ... But im not sure wjat files to rsync bd,mail,site,etc i dont want to miss a thing

Thanks for your help

Regards

Danyb