I've found that, regardless of the ripeness of the pumpkin... once you cook it and freeze it and thaw it again... it tastes like you used green pumpkins. Like, just on the verge of being ripe, kind of green.
I don't know why this happens, it just does. Maybe it's my personal sensory issues at play. I don't know.
Your mileage may vary.
RE: Pumpkin Bolognese