this.
I run them as my everything tire (road/cx/whatever) all fall/winter. They roll fast on concrete which is a huge plus.
also:
What are you trying to accomplish? For me, let warmers are to break the wind off the legs. So either it's cold and dry, and they break the wind, keeping your legs warm... or it's windy and wet, in which case, probably no leg warmers are going to keep your legs dry, but at least they stay warm.
If it's raining, I'm generally in the mindset that I'm going to get wet regardless, so I layer with that in mind and focus on keeping myself warm, not necessarily dry. That said, I'm especially sweaty when riding a bike, so I'm wet normally anyway?
That all said, the nano flex castelli stuff has been great. I've had a pair of leg warmers forever which have served me well. A bit of water resistance to keep the puddle splashed away. If it's raining, I usually just go 3/4 length tights under the bibs (or knee warmers or 3/4 thermals), velotoze (they are fiddly, but great), and just embrace the wet.