I confess. I didn't like this blueberry/nectarine pie in Baking with Julia. So, I made it twice, once following the recipe almost exactly, and then making adaptations which I felt improved it immensely.
On the second time around, I used my favorite crust recipe (5 cups of pastry flour, 2 cups of Crisco or a combination of lard and Crisco, 1/2 tsp baking powder, 2 tsp. salt, 1 egg, 1 tbls. of vinegar and approximately 2/3 cup of ice water. I worked the fat into flour mixture with my hands, leaving some pretty big chunks of Crisco. I portion the picture into 6 ounce discs and freeze what I don't need immediately. This is the same pastry recipe used in the bakery for which I volunteer and it is a very popular way of making pie crust in Ohio. Look in any community cookbook from this area and you will find this crust recipe. A variation has been published in two of Marcia Adams' cookbooks (a Midwest cook) and the 200th Anniversary King Arthur cookbook. In my mind, it can't be beat. The egg helps the crust brown -- I hate a pale pie crust.
I also switched thickeners the second time around, going from flour to Clear Jel. I used four tablespoons of Clear Jel -- my new go-to thickener for pies. I used to use tapioca, but Clear Jel is even better.
And, I upped the baking temperature to 400 degrees. This, too, helped the pie brown.
I'm not sure after making this pie twice that cooking part of the filling on top of the stove helps in the overall flavor. Since I make a lot of pies and taste a lot of pies at the bakery, I can't say that this method improves upon the end result. Plus, it's an added step that takes time and dirties a saucepan.