Wearing rain gear is basically to keep warm because it creates an ecosystem that keeps the elements out of your body at a specific cycling effort. The elements itself can act as a coolant, which can then reduce your body heat. Your cycling jacket is not an effective insulator, so you need to keep a specific cycling effort to prevent yourself from getting cold. But because you're cycling, you'll be sweating and then you will eventually get wet. You can prolong from getting yourself wet by maintaining a lower effort by not spinning so much. But then, when you tour most of your gears are low enough that it's hard not to spin so much and so fast. So yes, eventually you'll get wet from your sweat. I own 4 cycling jackets (1 Goretex XCR, 1 eVent, and 1 lightweight and breathable and 1 nylon) and 1 MEC cycle rain cape to reflect the conditions and cycling effort I'll be in. You'll just have to experiment with them to find what works best. If I'm in the tropics, I don't bother with a rain jacket anyhow. It's so darn hot outside that any water is a relief!