Our guild uses a Loot Council system. This system prioritizes performance, attendance and what we believe is best for the team as a whole. We will often funnel gear in to certain roles, classes or specs to meet certain encounter requirements.
Trial's in our guild are ineligible for loot until such a time as you pass your trial (assuming you do so). This means you can and will be passed over for a main raider, regardless of what you currently have equipped. You may occasionally be lucky enough to be awarded loot over a main raider, however this is extremely unlikely and is normally done by the good graces of the intended recipient.
Out loot council consists of five members who discuss and vote on who receives loot. Occasionally we will request that people /roll on a piece when a tie break is needed.
Having said this we generally like to promote an air of collaboration within the guild, this often means that our raiders will work out who receives what between themselves. Additionally it's a common scenario for our raiders to pass if gear is a larger upgrade for other members. This behavior is encouraged and it helps to foster the teamwork that define's our guild.