Based on my testing it would appear no. There's 2 issues I can see at play. The first is the required app functionality of the feed relies on the bundle ID. If that were the same across your versions (I.E. you used "Mobile MGMT" to name all your apps) then as far as the agent is concerned, you've already got the program. Even if you have a newer version in the feed entry, I haven't been able to get it to pop up requesting install.
So in theory it would work if you changed the program name but used the same App ID, I tried this however I still don't get a pop up. So I tried to manually install it from the Apps tab, however it will just sit on "Installing" and not do anything. That brings me to the second issue, it really seems like the agent can't install over the top of itself when it's open (which would make sense).
I'd say your best bet is to target the users you want to update via e-mail and inclue a link to the plist file. I.E:
itms-services://?action=download-manifest&url=http://mdmserver/mobileagent/MDMAgent.plist
The above works fine for us, it replaces the existing app and no need to re-enroll as long as the agent was functioning properly in the first place.