**Pic is photoshopped definately**
On Topic:
I think everyone's got great opinions, and I agree. It's a guideline, but as stated above, 38kts for the 777, that's pretty much a max anyways. My take on components above demonstrated are that you if you aren't proficient, 50% MDXW is your max. Avg pilot can probably take MDXW, and a proficient pilot in most cases can take 150% MDXW with a fight.
It's when you get 100%+ you need to take precautions in aircraft configurations and alternative airports as a better option. Personally, I just keep the flaps up and use differential thrust in my twins, and I've taken 200%. If I was in a single engine plane, high-wing I'd take maybe 125% max, low-wing 150%. Just based on it's weight vs speed @ landing etc...