Lightweight Raincoat with windstopper?

Kevin, I have a couple of opinions, but others might disagree with me.

Many people love their windshirts (ie, the Houdini and others), and find that they provide plenty of protection from the wind and a lot of warmth for their weight under windy conditions. Those windshirts are far more air-permeable than any WPB material (even eVent and Neoshell). So, I think the claim made by WL Gore that a WPB material can't be both very breathable (air permeable) and windproof is a FUD tactic (Fear, Uncertainty, and Doubt) meant to protect the Goretex market share. Any current technology that is waterproof is also windproof, and the highest breathability generally translates into the most comfort (and the least wetting of midlayer insulation).

Also, I would urge you to read user reviews before investing in 2-layer (or "2.5 layer") WPB jackets. The "2.5-layer" gimmick is just a pretty design printed on the inside of a 2-layer material. It doesn't meaningfully improve the lifespan of the membrane, in my experience. Marmot and other companies would probably claim that the design is printed with magnetic inks that improve circulation and athletic performance if they thought they could get away with it. My Marmot Mica (which is very similar to the Essence) was peeling apart in sheets before I'd had it for a year, and even when new the breathability was abysmal.

If you want something that is light and cheap and one step more durable than Driducks, and breathability isn't important, the category that includes the Essence, the Mica, and the TNF Triumph (and a few others) might be just right. If you can accept even less durability, you can get much better breathability, lower weight, and a lower price with Driducks. If you are willing to spend more and carry an extra 3-4 oz, you can get much better durability and breathability with something like the Montane Air.

I have been quite happy with my Rainshield O2 jacket and pants. They are very breathable, the fit works for me, and they have stood up well to the challenge of being under a backpack. In large, the jacket weighs 6.0 oz., and the pants 4.15 oz.. I see that they are available on Amazon for about $20 a piece, so it would not be too expensive an item to try. I much prefer the fit and feel of this rain gear to Frog Togs or Dri Ducks. Note that, at least when I bought them, they were only available in yellow. I like the yellow since it brightens up a rainy day.

My first rain jacket was made from ordinary polyurethane waterproof (not breathable) fabric and it was windproof. I later replaced it with a gortex rain jacket and it to is windproof. My current rain jacket is made from Event and it is also windproof.

I have been disappointed with the breathability of my Marmot Essence. It seems to be pretty waterproof, but I sweat so much wearing it that it is sometimes hard to tell. The specs look good and I have no big problems with durability and it is light, but don't expect much breathability in my experience. YMMV. I've gone back to DriDucks. So much more comfortable.
-Mark

A highly breathable windshirt is an article of clothing I wear a lot. A rain shell is not something I wear except in the rain.

A breathable rain shell doesn't breath enough for me to be comfortable in on dry or even misty days.

So I'm one of these people who don't consider a rain shell a substitute for a windshirt.
I DO feel that a windshirt can take the place of a rain shell in light/misty rain.