It this weird in-between season it can be hard to get the right level of warmth on your bed. Many buildings have finally turned off the heat for the season, but then a cold snap comes and you're freezing...
I think a lighter weight wool layer is good for this dilemma. A thin wool filled comforter is great especially if you don't want something too puffy (like down).
If you do like puffiness, then a summer weight down duvet is good. I find the "summer weight" concept for down rather funny. It's "summer weight" if you crank the A/C up really high and it's cold in your house... otherwise the down is just too warm. That's why a summer weight is actually good for right now.