I got the lightweight R4 as a replacement to a regular R4, which I recently lost on an airport shuttle. The lightweight R4 is more comfortable than the regular R4, due to less bulk. Indeed, it is a pleasure to wear. However, the regular R4 was a A LOT warmer. Sometimes I got overheated in the regular R4 (I live in South Carolina), and the lightweight R4 gives a good comfort range between 40 to 60 degrees F. I think the lightweight R4 is best for above freezing casual wear or aerobic activity in sub freezing weather. If worn over a sweater or lightweight fleece top, the lightweight R4 should works as a casual winter jacket on cold days.
Great lightweight jacket for fall and winter. Ive tryed many. No other jacket is comparable.