Migrate from x86 to x86_64

[eaperezh]

Hi,
I have a server with 5.0.5 open source edition in a centos 5.0. Both binaries are x86.

Our server was upgraded from 2 GB RAM to 8 GB RAM. And our user base was also incremented.

Reading the performance optimization page at:
Performance Tuning Guidelines for Large Deployments - Zimbra :: Wiki

I found the recomendation to move from x86 to x86_64. So some questions arise:
a- how to perform a backup of mail settings and mailboxes in the x86 version than can be restored to the x86_64 version?
b- I went from 500 to over 3k users, single domain. Will I really benefit moving to x86_64 in this config? (performance/stability)

your suggestions are welcomed, specially in the backup/restore part.

Thanks,

[eaperezh]

I was thinking of doing this:
a- Take a full backup of /opt/zimbra (with zimbra stopped)
b- fresh install the OS in x86_64 mode
c- place the backup back to /opt/zimbra
d- download 5.x.x latest in x86_64 and run ./install.sh
supposedly, the install.sh script will take care of reinstalling the binaries and preserving the data, right?

ideas?