No. He shouldn't be playing Hailstorm at all. Hailstorm isn't worth it, not even with both Legendaries. Ancestral Swiftness and Hailstorm with both are almost entirely the same damage output.
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Don Lionheart: You should be doing way better on most fights, especially things like Botanist where our cleave comes in or even Tichondrius, where you can mostly tunnel the boss. It seems you're having problems with keeping up Fury of Air on some fights, as I see 2 - 3 casts in some of your fights. You should try to keep up enough maelstrom without ever letting it drop off, as its a wasted GCD that could be used for rebuffing, procs or gaining ressources. Also, besides using Crash Lightning to activate Alpha Wolf and your cleave on fights where it matters, you shouldn't be using it.
Besides that, Other classes will out dps you mostly, especially on cleave/Aoe and some classes are pretty strong in singletarget. You're also missing your setbonusses, which gives you some more damage output overall.