Goretex shells don't breathe adequately in the rain for fast movers - they rely on "moisture gradient diffusion" - which means they need dry air outside to get rid of sweat. Which, of course, is insane.

Paramo make waterproof technology that is sort of super-wicking, so it still pumps sweat away from you in the rain. It works amazingly well but it does add some insulation. If you need to go lighter again, get one of the British designed membrane-less mid-layers that work on the same principle and wear it as your only layer - they wick well, are warm while wet, windproof and at least resist rain.

But I'd be surprised if the Paramo was too hot at 50F (that's 10C?) as long as you get the "Velez Light" model - the breathability means sweating actually cools you, so a VL over a T should be cooler than Goretex over the same T. Plus the fabric is flexible enough to let you roll the sleeves up, there are big pit vents, etc. You would have to order from the UK though.

http://road.cc/content/review/24252-...re-light-smock

Bad news: these don't pack small! We're talking coconut sized. The philosophy is you live in them!