To answer the original question: It depends on both the weather as well as the gear. I use a fleece jacket with a very clammy windshirt when cross country skiing. The windshirt is fairly waterproof, but not very breathable (I only use it for this -- otherwise I would get rid of it). If it is really dumping slush (common in the Northwest) then I put this on over my fleece. This is all happening while going uphill. I zip and and unzip quite a bit since I tend to sweat a lot. But by having at least my arms and shoulders covered, the fleece doesn't get soaked. It works, but mainly because at some point, I get above the freezing level, and it turns to snow. Then I can put away the windshirt, and just use the fleece. If I stop for lunch, then I'll put on my down jacket. While going downhill it is the opposite. I use the windshirt for wind and don't worry about internal moisture, since I'm not sweating much.
I've done it for summer day hikes and regretted it. I got caught in a nasty Sierra rain storm and got pretty well saturated (using a different windshirt). Generally speaking, most winshirts get soaked, so they don't offer much protection. A few degrees above freezing with saturated clothing is not pleasant and potentially dangerous.
Personally, I would carry a Propore jacket if you think there is a chance of rain. It offers the perfect combination of breathability, weight and water protection. If it wasn't for the fragile nature of it, then everyone would carry one. It works fairly well as a windshirt (it is more breathable than some windshirts). But I don't carry it when I go bushwhacking, and neither should you. But 99% of my hiking is on the trails or above treeline (when I do go off trail) so I don't worry about it. I've had the jacket for years -- it has a few holes, but Goretex wears out as well (and in a less obvious way). If you bushwhack a lot, then the compromises get a lot tougher.