From the MA 4.5 patch2 readme document (https://kc.mcafee.com/resources/sites/MCAFEE/content/live/PRODUCT_DOCUMENTATION/ 22000/PD22895/en_US/MA_45_Patch2_update.pdf), I see that this will work with ePO 4.0.
Yes you can upgrade the agent to version 4.5. Agent 4.5 is fully compatible with ePO 4.0.
There should not be any problem with ePO 4.5 and agent 4.0.
To compare the feature of MA 4.0 and 4.5, I will suggest you to refer to both the release notes.
I'd update the agents now.
I'd also get your ePO server up to date too (4.0P7) if you're planning to do an in-place upgrade to 4.5P3 or later, anyhow.
You'll have problems upgrading otherwise.
Thanks for the advice. My upgrade path is to go to EPO 4.0 Patch 7. I have read that it is a requirement before upgrading to EPO 4.5 or later. Was trying to wait until we get the server virtualized just incase the upgrade failed. Having the server virtualized would make it easier to restore after a failed upgrade say to Patch 7.
Will start testing the new 4.5 agent next week. It has been a busy week for us testing and deploying VSE 8.7 Patch 4 to all our clients.