I'd like to set up a small POC environment with SCCM 2012 and other 2012 products, but I'm not sure what risks I take if I extend the schema or have the servers running in the same AD domain as our production 2007 site. Can the two coexist in AD and over the wire as different primary sites?

Hi, The AD schema extensions are the same for SCCM 2007 as for SCCM 2012 so you don't have to extend it again. As long as you don't overlap the boundaries it will be fine to run a POC in the same AD as the production environment. I recommend that you use a dedicated VLAN for testing, I do this kind of setups all the time. Regards, Jrgen-- My System Center blog ccmexec.com -- Twitter @ccmexec