One of our main healers in our guild is 100% colorblind. While we will joke about the fact that, to him, everything is black, white, or grey (light black and dark white as well), that makes some things difficult for him. Hand of Gul'dan scares more players without visual impairment and they have to learn not to run out of it. Our healer literally couldn't finish Heroic Vortex Pinnacle because the floor, the background, the winds, and the tornadoes on the second boss all blended into the exact same shade of grey blur for him. Fortunately, that is no longer the case so it would seem that someone did complain and Blizzard tweaked things enough for folks like him to survive it.

It's a shame that colorblind mode, in the default UI, doesn't fix that but I can't imagine the amount of graphics assets that Blizzard's design team would have to go through to make sure that everything had discrete shades and hues.

Thank God i'm not 100%, but I'm told I might be later in life :(

The Skywall instances have been a pretty big pain, and I feel for your healer on the switching winds boss. This and a few of the bosses in Throne of the Tides really gives me issues. Also, some of the bosses have taken to using smokescreens like the guy in Stocks or Heroic Deadmines which make it not fun to try and pick up targets and tank.

I have learned that there is almost NO way for Blizzard to fix everything in the game so people with this issue can see it as well as those without it. That's the problem with being "handicapped"...we, by definition, are the minority.

I know I'm late to the party, but you may wish to look into an addon called GTFO. It buzzes when you're standing in the fire (or anything else that's bad) and stops once you're out of danger. It's great.