This is a very useful article. The author (http://gossamergear.com/wp/rain-guide-to-backpacking) is certainly right that after a while you are bound to get soaked to the skin. This may mean you have to camp early to get yourself under a roof and warm up (See: http://www.theultralighthiker.com/the-importance-of-a-roof/) or it can be avoided by using an umbrella or (I have found) a poncho. If the poncho can double as a shelter (See: http://www.theultralighthiker.com/pitching-the-poncho-warning-this-may-save-your-life/) or a ground sheet (See: http://www.theultralighthiker.com/the-deer-hunters-tent/ or http://www.theultralighthiker.com/zpacks-hexamid-solo-plus-tent/) this will cut some of the weight penalty of carrying it though at only 165 grams (for the Montbell) it might be worthwhile anyway.
PS: I have only just discovered this wonderful website: https://myopencountry.com/hiking-camping-tips-guides/environment-safety/hiking-rain/ Amongst many other great posts, there is surely this definitive article on the (joys of) hiking in the rain!
Photo Above: Gossamer Gear Liteflex Umbrella 240 grams