Not to high to float that is for sure. It just flattens out the higher it goes, in turn making it technically easier, but a faster float for sure. The sky is best fished between 3,800 and 8,000 cfs. Sultan and down is a very tame float on anything above 3,500. High bridge to sultan can have some tricky spots at any cfs but there are a few that get worse with more water up to a point anyway. Hope this helps. I have been waiting for the river to come up so it will be worth while to fish it, it has needed some color in a bad way for a long time. I would love to float with you if you needed a turn, as it is hard to find others to float with, I have a cataraft and float the sky all the time, but money is tight right now unfortunately. If you ever need someone in the future shoot me a message. And +2 on fishing it on the drop.
Tight lines,
H&F