Eurip has a good post over at OutDPS about if/when it's good to roll on leather. This is an interesting topic in general and specifically. First let me go over the specifics. Everyone's BiS is somewhat different given what gear they currently have. So let me use my current gear as the starting point for this very specific view. I had been planning my upgrades last week. I went to http://www.femaledwarf.com/ did my thing, and clicked on the link to my Custom Hunterloot.com Gear Ranking. These are the leather pieces that came out best for me:
Bracers of Dark Determination (BiS Heroic for me)
Bracers of Dark Determination (BiS Non-Heroic for me)
I'm actually planning on having Crusader's Dragonscale Bracers crafted instead. Is this a dumb waste of gold? Probably not in this case. I could get the leather non-heroic ones, but I don't roll on leather against DPS ferals or rogues. And the crafted ones are a little better -- and can be a lot better if I pick up a little more incidental hit elsewhere so both my gems can be +20 agility.
Leather Hands, Waist, and Feet
Gloves of the Silver Assassin
Belt of the Merciless Killer
Treads of the Icewalker
Generally Heroic ToC items will be better than non-Heroic ToC items. For me, none of these leather pieces are BiS compared with their mail equivalents. Sure I would take a +83 dps upgrade for the gloves. I don't care too much about having a 4 piece Windrunner set. However, the mail Heroic equivalents are better.
ICC and the Future of Mail
The question of leather vs mail for hunters will become the new factor in the "Is this an up for me?" theme. When hunters lose their mana ingredient, intelligence will no longer be a desired stat. What will distinguish rogue gear from hunter gear besides the mail vs leather tag? Will shamen be the new hunter-loot! meme?