Alright I have determined that through the non-answer of this post that there is no "need" for a frontend server in this configuration. But one of the IMs I got on this subject from my buddy Jeremy pointed out something I had over looked...
In this config a frontend server would provide close to no security advantage, you would have to make your way through the stateful and stateless firewalls and load balancers before talking to IIS 7 (which is pretty rock solid as is, even without the stateful and application firewalls). BUT another layer or another group of machines is another layer of security, albeit security through obscurity. So though minimal the frontend adds "some" obscurity/security.
I'm still not decided what I will do as I kind of feel like all the ports that get opened for a frontend on the DMZ to talk to the backend and the DCs/GCs are enough for someone to make their next hop, after all they just made it through at least 3 layers of security making it through another, one that has half a dozen ports and at least 3 protocols open, isn't the difficult part once you are that far.