Don't go 0/30/21 spec its not good. It's way too slow and you shouldn't spend time healing if you don't need to. I've gone through every possible spec for shaman. (
http://db.vanillagaming.org/?talent#hAbzxcZxifzm0ut) This is the most efficient and strongest melee shaman build you can do. Nature swiftness build, while it looks like it can work or even be better for 1v1, it's not. You are missing out on an extra auto attack, which is huge since it can crit and windfury, and 20% more damage from earth shock. On top of that, you are missing the 1 second off earth shock, and eye of the storm.
The healing kickback protection is trash since 70% isn't enough when a rogue or hunter is on you. In a fight, especially as shaman you want to be as efficient and quick as possible to eliminate the opponent. You can't dilly dally autoattacking like a paladin and pretending you're a healer, you don't have that much mana or mana recovery. If you don't have the 1 second cd removal on your earth shock, also with improved grounding, you will get sheeped. If you get sheeped you die. It's also important against warlocks and other casters too, much more important than a 1.4k heal once in a fight. The point is you shouldn't put yourself in a situation where you need that heal. Otherwise, a free chain lightning once in a fight is like 500 damage its not worth it. Stormstrike gives you a free minimum 400 damage every 20 seconds, while buffing earth shock.
With grenades, you can easily get a full heal off anyway, why do you need NS then? Also, eye of the storm is much better for casting a heal/lightning bolt (you shouldn't ever have to cast lightning bolt anyway) since you can make a /sit macro.
Make sure you get the improved earth totem too, since at 12 yards it will usually give another tick of slow.
Also, the improved totem range is detrimental, since first of all you should never use the buff totems for pvp its a waste of mana, and secondly, you want to be able to weave in and out of your grounding totem, to avoid it being killed by the wrong spell.