My own experience is that wool batting is no warmer than regular batting. I think if you want "warm" you need to go with something "heavy" like cotton.
Wool is actually the best for all-season use because it "breathes" whereas poly does not.
The Dream Wool is not lumpy...it is very uniform. However, it does shed small bits from the edges of the batting until you get it bound. My quilting room looked like I lived with 4 long-haired dogs until I got that sucker bound! LOL I had to clean my floor VERY frequently to keep the sheds cleaned up!
Our wool quilt is the one we currently have on our bed (along with a topsheet) even though we are currently having a heatwave here. And it is because the wool does NOT feel too "warm". It feels very light.