I got myself a black (would have liked camo but it wasn't in stock) RainCoat Pro. The standard would have worked just fine but for the small extra sum I chose the Pro for the extension part just i case I would ever need it. A short review of how it worked with the lenses in my short short testing in snow.
Ease of mounting:
At first it was a bit confusing how to strap it on an extremely extending zoom that the 150-500mm is. After some experimenting I found a couple of different variants. The 70-200mm created a lot of loose textile hanging around but most of it can be hidden and snared up with the straps.
Quality:
Directly out of the bag it simply feels solid. It is very thin and even more impressively lightweight but yet it feels very rough and tough. All seems are well done and the textile straps are really soft (in a good way) and therefor easy to work with. It breathes but you can feel your hands warming the air inside the sleeve. It looks very waterproof with no moisture inside despite big water drops on the outer surface.
Comfort and function:
So far I got some things perfect but I still have trouble with primarily one thing.
To start with the bad part, I got trouble strapping it so that the camera side textile don't get pushed to my face during zooming out with the 150-500mm without blocking either the zoom or the focus ring. The results in a tough time seeing the LCD and an even tougher time getting my eye to the viewfinder without first having to push the excess textile back up with my nose. Hopefully I can find a better way to mount the coat. Also reaching controls on the left side side is a bit hampered, if you tighten the cord on the back of the camera, due to the lack of sleeve on that side.
Other than the first negative part it actually works better than expected. The thinness and the softness of the material makes no to almost no force to hinder zooming, focusing and camera controls. One big bonus I found is that the velvety finish actually slows the water drops movement and minimizes potential splashing and therefor limits the risk of drops traveling in from outside of the coat. Another bonus is that it really muffles the shutter sound, the dampened sound together with a K-5 is awesome. However I recommend adding a protectional filter on the lens as the snow often found its way into the hood due to wind.
I would love to have their neoprene hood caps too to complement this setup.
Got any question, just ask!