Well, I would rather be a little sweaty. I hate riding in the rain, but I had 4 days of torrential downpours on my tour last summer, and I decided I needed a better fitting rain jacket.
I bought the Shower's Pass (not sure which one, definitely not the most expensive). I haven't had a chance to use it, but the number one thing i see as different from the 3 other rain jackets I have had, is that the material is extremely thin and not hard, like the other ones. There are very large pit vents and a mesh vent in back.
I know wool keeps you warm while wet, but riding in the rain, even at temperatures of 70-75 leave you open to hypothermia, which can happen very quickly. I had the most unpleasant experience of getting caught in a strong rain, about 8 years ago, wearing just my wind jacket. It was probably in the high fifties, low sixties. DH and I booked it back to our car (he had a rain jacket on), where I proceeded to strip and let the heater warm me full blast, while wrapped in a beach towel I found in the car. I shivered for hours afterwards, despite the fact it was probably only 8 miles of riding in the rain. It was scary.