BES upgrade 4x to 5x – Re-activation of users?

We have a decent sized BES environment with just over 400 users. Our current BES 4.1.6 is on a virtual server (one instance only), and we are planning to take the plunge to v 5, via an in-place upgrade.

We have done a bit of testing in our test virtual environment, and found the upgrade to be pretty easy. However, my biggest concern is, will we be required to re-activate our users once the in-place upgrade is complete? If anyone has come across this issue during their in-place upgrade, or have any advice, it would be much appreciated! Am really worried that we would have to be re-activating 400+ users’ devices if something goes awry?

Thank you!