I'll keep going during rain. In New Zealand you don't get all that far if you stop for rain. Having said that, it's better to take quiet routes if it is wet, as automobile drivers don't seem to alter their driving speeds to suit, or care particularly whether the risk of hitting someone is increased by poor weather.
My rain jacket is a mid price, semi breatheable type, such that you also keep warmish with it on. I recently rode a solid 9 hours in rain, much of it crazy heavy, and was mildly damp by the end of it. It was nice to get in that hot tub though...