I cook my Fall decorative pumpkins when I'm done with them. They are more watery than pie pumpkins but oven roasting evaporates some of the water and gives you a chance to pour off the rest.
I have found pies made from fresh pumpkin to be much lighter in texture, almost like a souffle. Lighter in color too.
As a convenience, I package my cooked, blended pumpkin in 2 cup servings in freezer bags as that is the amount called for in most of my recipes. Pop them in the freezer and use as desired. Yum!
I agree! I have just processed 2 large "field" pumpkins and several "pie" pumpkins, and really found no difference in taste. I have taken advantage of clearance prices on pumpkins to put up several quarts of pumpkin which I use as a vegetable (mashed, just like any winter squash) and to make pumpkin soup as well and breads and pies.