Well, this was probably my 15th AG, but only my 6th 10 gallon batch in my mashtun. Previously I used a brew in bag variation which probably wouldnt have worked for this beer. Due to the pumpkin in the mash, however, I had my first stuck mash/sparge !! (even with the pound of rice hulls I added.) To get out of this I turned off my ball valve and did my best to clear all the grain away from the braid, the grains I was pulling up through the rest of the mash were very very dry, so I could tell what was wrong. I ended up adding extra sparge water until I reached my pre-boil volume and dumped the rest.
If you're going to do this as your first AG brew, I would NOT pump the pumpkin in the mash. Pump most of the pumpkin in the beginning of the boil and save a can for the last 10 min or so, it doesn't really matter, but if you put it in the mash you're probably in for a major learning curve.
Also, if patience is not a virtue, try something with a quicker turn around time for your first AG, you could be sampling it within 5 or so weeks instead of waiting for the spices to mellow in this. Good luck, let us know how it goes!