I use a birdiepal lightflex, which is nearly identical to the golite chromedome or whatever it was called. I carried it for most of the CDT last year and loved it. The umbrella is great in hot desert sun for personal shade (and you can take your hat off to cool your head). It works very well for light rain and on/off rain showers. Mine stays in the side pocket of my pack and I can grab it on the go instead of having to stop often to put on/take off a rain jacket. It also allows me to wear either a t-shirt (hot weather) or breathable wind shirt (cooler weather) and not sweat too much while hiking in the rain.
I also use the umbrella weighted with my food bag tied to the handle as an extra mini-vestibule outside my tarptent, often for my shoes and stinky socks.
Since I still carry full raingear, I consider the umbrella something of a luxury item and it doesn't come on all trips. It is awful in the wind and if you use trekking poles (i don't) you would have to trade off one pole for the umbrella or somehow rig it over you. It also obviously doesn't work well while bushwacking or on overgrown trails.
I have an older, non-breathable cuben rain jck from Zpacks. It fits down to the top of my thighs and has pit zips, but being able to not wear it while hiking in light rain is nice. It is way lighter than a breathable jacket, which I no longer need, since I have the umbrella. The umbrella and long rain jacket allow me to leave rainpants at home for short trips in summer, when I'm not that worried about my legs getting overly cold.