After seeing how much faster and more stable the 10549 build was on my Lumia 635, I decided to go ahead and put it on my main device too, which is the Lumia Icon. I did a full hard reset after installing.
So far I'm happy, but I've not used out that much yet. It runs just as fast as 8.1, if not faster actually (just like on the 635). It still has several smaller bugs and some more major (like I can't install any non English keyboard dictionary), but no deal breaker so far. By far the best and most stable build so far, way faster than 10536.