I've been using Pearl Izumi AmFib tights for several years and they are incredibly warm. However, I have found that PI gear is sized very inconsistently. My first PI tights fit me great in size Large, so I bought my AmFibs in L but they were much too small and I had to exchange them for Xl. I recently bought some PI Select tights in Size L (which cost $70 full retail but I got for 25% off at REI) and they also fit too small, so I again exchanged for XL. Their jerseys and jackets fit the same way -- some styles fit me perfect in Large and other styles I have to go up to XL. I don't know why they can't size their clothes consistently.