"There's the mid-price, Gore-Tex Paclite or proprietary jackets that wet out after 10-20 minutes of rain, but serve well for setting up a tent in the rain and getting through a squall.
Then you've got your 3-layer and eVent raincoats for sustained rain, so you can hike while it rains or stand for an hour in a storm."
There's not much I agree with in this post. It doesn't sound like you understand what "wetting out" is because it has nothing to do with the membrane. How fast a jacket wets out is determined by the quality/durability of the DWR (durable water repellant) treatment on the outside of the nylon. Membrane and internal layers have nothing to do with this.
Once a coat "wets out" (which is water soaking into the external nylon) then the water has arrived at the membrane and it should still keep you dry unless the membrane is damaged or sucks. The reason you don't want a coat to "wet out" is because the breathability goes way down when you're got saturated material on the outside of it (there's no capacity to accept moisture coming through the membrane).
Some crappy PU coats are great for standing in the rain for hours, they just don't breath as well. The main difference between 2.5 and 3 layer jackets is that 2.5 is lighter, while 3 layer coats are heavier but last longer because there's protective fabric inside the membrane.
OP: If you're looking for a really light rain jacket, look at the offerings by Marmot, Haglofs and Montane but skip anything with Pertex Shield+ because that membrane falls apart fast. They've all got women's coats in the 5-7oz range in their summer lines.
If you're looking for something light but longer lasting, I'd recommend a 3-layer shell like the Mountain Hardware Quasar Pullover. They make a women's version that is 7.8oz and for that you get it all: 3 layer, eVent. The non-pull over version is a lot heavier as there are other differences.
I'm sure there are other nice women's jackets as well. As usual with rain jackets, most of them are darn short which sucks when you're bending over setting up a tent. It's tough being a women because a lot of companies only make their nice coats in mens versions. If you're looking in the 9-10oz range, Haglofs Gram Q and Lim II are darn nice 3-layer womens jackets.