We're using SEB at the University of Cologne on virtual disks, used by Citrix Provisioning Services. Currently 150 computers are used for online exams and if there is the need to change something in the configuration shortly before or during the online exam, all computers have to be shut down. It would be very cool if there would be a option to use a shared configuration on a network drive. To secure the configuration file (i.e. hotkeys to leave seb, allowed applications), only the exam url, who changes every semester, should be in a special configuration file. At the moment our only option is to symlink the configuration file, but then smarter students could figure out the where the configuration file is located on. If there is only the exam url stored, it would be negligible.
I'm not sure if I understood your request for a shared configuration completely. But anyways, we are about to release a SEB major update (2.0) which will change the configuration procedure completely: SEB will be able to be easily reconfigured by opening new encrypted .seb configuration files. So then you will be able to generate multiple .seb files with individual configuration and when users double click on such a .seb file, SEB will start up and apply that specific configuration. You could safe the .seb file for the current exam on a exam portal web page, which users open with a standard browser, click on the linked .seb file which gets downloaded and opens the exam in SEB then.
As a second option the .seb file can be placed to the usual configuration directory and if SEB is started directly (not by opening a .seb file), it will use the configuration from that encrypted .seb file. This can be used as a kind of default configuration, but the idea is to open and configure SEB with the .seb files easily individually for each exam.
We intend to release SEB 2.0 for Mac and Windows around end of January 2013. The almost finished Mac version I intend to release as a public preview before Christmas already.
SEB 2.0 and later allows configuration to be stored on a server.