So far it seems that those that replaced the Grandstream behind the router did so because it wouldn't work properly in the recommended position in front of the router.

This makes me feel better, I thought there was some other reason for placing it behind the router.

I still wish someone from Voipo would chime in on this and let me know if there is any other reason to have the Grandstream behind the router other than only when it doesn't work in front of the router.