You can increase the size of the pbfs in the machine policy to support hundreds/thousands of users - performance decreases, network traffic increases, and security risks increase of course.
You can add groups of users to device nodes in epo.
Don't add more than a few hundred users - it's never a comfortable experience mirroring your entire active directory onto every machine.
Is there a way to see how much of of the pbfs is is being used so we can tell if we have plenty of space or should make it larger?
We have the same issue. Our solution was to turn on all domain users, have a single account with a profile on all shared machines that was used to get through preboot during the check in process, and have the user log in once to give them preboot access.
Increase the size of the preboot to 50mb then you should be able to add 600 + users. We have added all domain users to the preboot.
Message was edited by: mhedrick on 3/20/13 6:44:37 PM CDT