OT: Topic being Windwalker being unprogressable, that is total BS. Windwalker is competitive DPS with or without FoF.
Some fights it is not optimal to use FoF at all some you should if you know how. FoF is a DPS loss basically if you either energy cap whilst channelling or if RSK comes off cooldown.
All the people in here quoting their rankings, wow good job you ranked on fights with a class that is still being heavily tuned (I presume from Ghostcrawlers post) and even the stat priority is controversial.
Some people stack haste, some people stack crit, some people use FoF on CD, some don't use it at all. The class is so up in the air atm you should just be testing the waters with each and using whichever yields the best results for you.
25-man parses seem to be 10-15% higher than 10-man parses too. I am not sure how much DPS you get from 1 or 2 extra Skull Banners or Stormlash totems. I know that Stormlash totems are only about 1% of my damage overall with 3 shamans. So that's less than a 1% increase from the average 10 to 25man. I can't see Skull Banner being more than a couple percent. Does not account for the top-end parses being 10-15% higher on 25-man except that the best players generally play 25s.
Your Garajal 10-Heroic parse, for example, on 25-Heroic you wouldn't even get in the top 100. I'm guessing the reason you got that was because you do the logging. Because of the split realms, people who do the logging themselves will always have better parses. So you're only competing with a fraction of monks there.