Hatson

The bladestorm isn't an auto attack, it's more of a channeled spell in on itself. So the spin attack itself cannot proc windfury or flurry, because it's not your own auto attacks that are doing the spin damage. It's an entirely different effect by itself. However, on old Nostalrius, you could cast spells and even auto attack during the spin, at least in the early days of Nos when I played. It was broken as hell. Not sure if that's still possible here.

It does only absorb one spell, every 10 seconds. But if the spell doesn't do damage, it can't kill the totem. And you can't put DoTs or debuffs on totems, so it absorbs those without dying. But since it absorbed that spell, you still have to wait 10 seconds before it absorbs anything else again.

Early on though the hit % build will likely help more. But later on as you get better gear, and increased debuff limit on the target (Winter's Chill and such), the Elemental Devastation build will become more and more relevant.

You will only be getting 2.5 extra mana every 2 seconds from the mana spring, and you'll be in the melee group in all groups and raids because of improved WF + STR totems, so you will always be the only one even benefiting from the mana spring, which only grants you 75 extra mana over the whole minute duration of the totem. That's basically you paying 5 talent points just for a 6,25 mp5 stat. You feel that's worth 5 talent points? You won't be running into mana problems as an Enhancement in raids, unless you are using it all on max rank shocks in raid. But you're not really there to compete with dps, you're there to bring Nightfall debuff and impoved totems for the melee group. Your consumables, potions, food, runes, and flask of distilled wisdom is more than enough to keep your mana good through any fight. You also won't be healing. So reduced healing costs is trivial. You also don't really need reduced mana cost on totems, because you won't be running out of mana unless you're spamming max rank shocks (which would make you oom fast no matter what you do). The only beneficial thing from going down Resto is the 3% hit chance on melee and spells. And that's the only part of it that is arguable to take over Elemental Devastation. With 10% spell crit chance (which is not hard to get with the gear + consumables), Elemental Devastation has on average 20-25% up time. That's an average of +2% melee crit chance. Every 1% spell crit = 0.18% melee crit And you also get Clearcasting, which is great for using max rank shocks, without having to worry about running oom. And if you do find yourself go oom (you went to greedy on shocks, or the fight went on too long), then you can continue spamming low rank shocks every 5 seconds for less than 20 mana cost (or 0 cost if you use a macro to switch to Spirit of Aquementas between melee swings to cast shocks for FREE) to always have a chance to proc Clearcasting and Elemental Devastation, both which increase your DPS. Mana isn't the biggest issue since there are many ways to work around it, even tricks like Aquementas hotswapping (pre-item buff patch). It's mostly just a decision between 3% hit or more Crit and Clearcasting. Of course, if you go with the Resto build, you can switch that 3% for 3% more crit instead on the items, that's a possibility. And then you could be debating Clearcasting vs ~ 1% crit. In any case, both options are viable imo, it just depends on what your current items are like. Of course, the better stats you get, the more attractive the Crit/Clearcasting build becomes, but that's only assuming you are hit capped via your items (which you might not be). I'm just comparing the 2 options, feel free to add onto it if you have anything to say about it.