Office365 - OST download size and managing it.

We have 400 users and we are using Microsoft Office365 Enterprise (E3).  The mailbox size of few users more than 25GB (Just 3 months data).

If the user moves from one computer to other, the entire mailbox will be downloaded via internet. This consumes high bandwidth. In case more than 3-4 users shift per day, all other users experience slow internet access.

I have read the performance blog:

http://blogs.technet.com/b/askperf/archive/2007/01/21/network-stored-pst-files-don-t-do-it.aspx

So, will not be trying to re-direct OST/PST files to network location.

Requesting some experts advise to overcome this problem.

Thanks.