Welcome to WTW Paul.
I bought a new FWC Grandby in Oct '07. I went thru some of the same thinking you are doing now. It's a big chunk of money to lay out. I couldn't find a used one, especially as far east as I live. Anyway, after the recommendations from the folks on this forum and talking to Sean Dempsey, a FWC distributor in Eagle WI, I went with most options.
However, I did not get the hot water system and I don't miss it. I bought a Zodi Extreme shower
http://www.zodi.com/web-content/Consumer/zodiextremeshower.html and an Outback Porta Priv
http://www.evergreen-outdoors.net/outback/porta_privy.htm.
I was surprised to find that I don't really use the awning very much, but it's there just in case. I have a powered roof vent over the bed and we love it. The rear roof vent is not powered, but I plan to upgrade that someday to help vent cooking smells. I don't have the aux battery system because my truck has an aux battery. But that may be a problem in the future if I get a newer truck that doesn't have a place for an aux battery. I really like the 3-way frig because I love ice cream at times.
The rear flood lites are nice. Definitely get the screen door! I don't know if the Hawk model has an extended bed option or not, but I recommend that. I also recommend the porta potti.
The way we camp, the mini dinette would be a very nice option. It wasn't available in 2007. I may add that mod to my Grandby someday.
One thing that I didn't like about some of the older model FWC's were outside storm flaps on the windows. I think FWC started building them with inside storm flaps sometime around 2003 or 2004?? Stan or somebody on this forum may know for sure when that started.
IMO, one advantage to a new unit is that you get all the latest improvements and cool features and they fit the newer trucks.
Have fun deciding on your purchase. You will enjoy it when you get it.