Configurator 1.4.3 Inconsistent updates

I'm the "ipad guy" in a middle/high school. Just pulled in 110 ipads for Seniors to update the OS, apps, etc. and have seen extraordinarily inconsistent results. I'm hoping someone can illuminate me - or at least point me to the right direction - espiecially since I have several VERY angry students who lost things like college essays.

[....and no backups, of course!]

Most of the ipads were on OS 7.0.x, but many were still on 6.x

I pulled in the iPads, hooked them up to the configurator, selected the apps to add, selected to update the OS, and hit refresh.

• Most ipads updated just fine.

• Several came back having been wiped - all personal data gone from the devices, and I had to go hrough the initial setup screens {Starting from the "Hello" all the way through network settings, iCloud backups, etc.}

I wish they HAD setup their iCloud backups - sadly, they hadn't.

• A few were wiped, put themselves into Recovery mode and need to be "reactivated" - and thus are not updateable using Configurator [according to Configurator]. Never mind, of course, that Configurator was used to set them up in the first place.

WHY the inconsistent operation, given the same procedures?

Any suggestions for avoiding this headache?

[These are all 16gb iPad 2s, BTW]