I made this last night and it is delish!  Brought it to work and it's gone already.
Made just a few changes---I mixed it in the food processor and it came out fine.  started with the butter and sugar, added the eggs, vanilla and pumpkin, then added the dry ingred last.  I used good melted choc chips with a bit of butter.  I don't usually like chocolate with "fruit" of any kind---no choc and raspberry, or strawberry or banana for me, I know weird.  But this was very nice and marbled well.  I also added about 1/2 tsp of cinnamon to the dry ingred.  I had to  bake it for an extra 10 minutes.  It makes a large loaf---I baked it in my silicone bread pan and it bulged a bit from the amount and density of the batter.  I will definitely make this again.