I am looking for a good winter jacket for riding in temps from the low 20s to high 30s.

I am looking at both the Castelli Espresso and the Alpha RoS and wondering which will is warmer.

Castelli says that the Alpha RoS is good down to 23F and the Espresso is good only to about 32F. However, I find this hard to believe. The Espresso seems like it would be significantly warmer, and the Alpha RoS doesn't appear to be that warm of a jacket and is quite a close fit so I don't think I could get a lot of layers on under it.

Can anyone comment who has one of these jackets?