Cue some suspense music. I’m going to delve into a controversial subject…
Hybrid classes don’t tend to be good examples of friendly coexistence, and shamans are no exception. On the WoW forums we find a small but vocal minority with a wide variety of opinions on just about every aspect of our class. There are roughly two extremes to be found; on the one hand we have the rigid, old-school types, and on the other (at lack of a better definition) the new and experimental generation. Compare the following claims:
A REAL shaman wears mail
A REAL shaman is Horde
A REAL shaman uses a shield
And if you’re not using a shield, then you had better be enhancement and dual-wielding two slow weapons
With:
It’s okay to wear cloth
It’s okay to wear leather
It’s okay to use a staff or some funky off-hand frillies
It’s okay to be Draenei
On first glance it would be easy to lump me in with the first group, being a mail-wearing, shield-bearing, Horde-as-can-be shaman. But the truth is: I love Draenei shamans, and my own little space cow is of course the cutest of them all 
But, seriously, the whole Alliance vs Horde debate is a complete non-issue. I for one am happy that shamans no longer need to be balanced against paladins (and vice versa).
There is one area where I’m more conservatist. It’s the eternal question: should restoration shamans wear cloth and leather?
A commonly heard answer is: of course they should, healers aren’t supposed to get hit anyway, so who cares about that difference in armour?
My own answer is: exceptions aside, no, they shouldn’t.
One reason for my answer is that the statement above is only partially true. Okay, healers aren’t supposed to get hit. Tanks aren’t supposed to lose aggro. Traps and saps and sheep aren’t supposed to break. But what do you know? Shit happens, and when it does, then all the little bits count for something.
But there is another, much more important reason, and this one requires some more in-depth knowledge of the game mechanics.
There are four healing classes in the game, and they all have their own special abilities, strengths and weaknesses. But they also share some common ground. More specifically; we have the “squishies”, which are priests and druids, and the “shieldies”, which are, you guessed it, shamans and paladins.
The “squishie” group can’t equip shields and are thus stuck with using some off-hand frilly or a two-handed healing staff. Both classes rely quite heavily on spirit, not only for mana regeneration but also for their raw healing power, with spells and talents like Meditation, Spiritual Guidance, Innervate and Tree of Life. Because they stack so much spirit, they benefit a lot from staying outside of the five-second rule. This in turn merits the so-called “burst casting”; casting a lot of healing spells at once, and then not casting anything for a while to regenerate mana. It’s no coincidence that both priests and druids have a wide variety of Heal over Time spells at their disposal; it is these HoTs that make burst healing such a viable option for them.
The “shieldie” group on the other hand is easily recognised by the big healing shields they tend to lug around. They don’t have any real HoT spells, Healing Stream Totem and Judgement of Light are nice little extras at best, and the Draenei racial has too long a cooldown to be properly integrated into one’s healing routine. As a result, shamans and paladins are often found casting non-stop, and they spend a lot of time inside of the five-second rule. The game actually rewards this constant stream of quick, down-ranked heals by talents such as Healing Way and Illumination, through the simple reasoning that the more often you cast, the more often you’ll land a crit heal. (Note that priests have a talent similar to Healing Way, namely Inspiration.) And when you know that there isn’t a single spell or talent for either class that is based on spirit, it should be no surprise that it’s of little value to them. Both shamans and paladins rely primarily on MP/5 for mana regeneration.
With all of this information in mind, go ahead and investigate what kind of stats are typically found on healing cloth and leather.
The answer: Intellect, Stamina, Spirit and +healing.
And what kind of stats do we typically find on healing mail and plate?
Answer: Intellect, Stamina, +healing, MP/5 and spell crit.
Put one and one together and you’ll understand why I claim that, exceptions aside, shamans should try to stay away from cloth and leather. A resto druid in cloth? Sure. A holy paladin in mail? I can see that happening too, although there is a lot of good healing plate out there. But a shaman in cloth? No. If they care about not only having a proper healing bonus, but also a healthy amount of MP/5 and spell crit (and yes, armour too), then mail is the only way to go.
You don’t have to take my word for this. There are some excellent spreadsheets available that will show you that, no matter what point of the game you’re currently in, the available restoration and even elemental mail items are much better itemised for resto shamans than their cloth and leather alternatives.
And yes, there are always exceptions. Would I upgrade my Rugged Mountain Bracers for Bands of Negation, if they dropped? Hell yes I would. Except that I’ve been trying time and time again to upgrade to Primal Surge Bracers, and as these stupid things simply refuse to drop I’m currently farming materials to craft myself a pair of Netherstrike Bracers. Elemental-oriented as they might be, they still outshine the Bands of Negation by a large margin.
In conclusion… all of this is just my opinion, based on my own research. As stated earlier, this is a controversial subject, but my arguments are debatable and my opinions are flexible, so if you have any thoughts on this subject, feel free to share 
