Basic scenario: we are a school (overwhelmingly Mac, some Windows machines via BootCamp), and we are considering using DeepFreeze to guard the state of our shared machines. We have roughly 250 machines that are either shared laptops (which move around quite a bit) or common desktops in public spaces. Obviously, we spend a lot of time maintaining the machines and trying to reverse the inevitable drift as people make changes to the computers. We would like to control the integrity of the build we initially put onto the machines without handcuffing users and especially without using Mac's Parental Control software. (We've had nothing but bad experiences with it.)

We've been testing DeepFreeze, and so far it's very impressive. But I'm curious to hear if people who have used DeepFreeze or any similar software have any advice or tips. To get things started, I will post my own pros and cons.

Pros:

1. The state of the machine is frozen in our chosen state. All changes made to the machine after that disappear upon restart. (This frozen state really appears to cover everything. I have yet to do something to a test machine that isn't instantly healed.) Tons of trivial but time-consuming maintenance is gone in an instant. Also, lots of not-so-trivial breakage should be avoided.
2. There are good options, however, that allow you to create storage spaces either globally or per user. (Otherwise, stored files disappear upon reboot. For some machines, this is a good option itself. Simply warn people: save externally or else; this machine is a kiosk, not your storage space.)

Cons:

1. Anytime we actually need to make a change (upgrade basic software, add a printer or an airport permanently, add new software), the process is a bit more complex. Reboot into a special mode (thaw state), make changes, reboot back into frozen mode. If (when?) we forget this, we will end up making changes that disappear after the next reboot.
2. Users will forget to save files correctly (in the right place or externally), and we will have loud, unpleasant conversations explaining that we can't recover the document they worked on all afternoon yesterday. The machine rebooted. The file is gone.

These are my initial thoughts, but I would love to hear from other people who have experience with DeepFreeze or any similar software. What should we be careful about? Do the pros outweigh the cons? What gains or problems am I not seeing? Thanks.