Raiding and Loot Rules

I was wondering if any of the two readers I have would care to share their guild's loot rules for raiding?

My guild has tried a few things, but being the way we are we've always decided to stick with generally simple rules, adding one now and again to further the best interests of progression, fun, or fairness.  While I personally think we have too many rules (and we're considering adding another one!), I do think our system works pretty well, is not too complicated, and is mostly fair to all involved.

Here's our rules:

1.  Rolls are called for main specs first, then off spec.
   1a.  Your main spec is the role you are performing on this particular raid.  If you wish to roll on a different spec, clear it with the raid leader first.
   1b.  If you have already won an item from either of the two main general categories we set out (see #2 below) as a main spec item, you roll as if it were an off spec item.

2.  There are 3 categories of items we separate:  tier pieces/trophies, normal gear, and random stuff.  Random stuff, for example, is Onyxia's Enlarged Onyxia Hide Backpack - everyone can roll on random stuff provided it's something they can use (i.e. they don't already have Onyxia's backpack.)  For the other two categories, winning an item in one category does not preclude you from rolling on an item in the other as main spec.

3.  We are working on progression and feel that appropriately geared tanks are essential to success.  In addition to anyone performing the tank role on the raid, our designated progression tanks get first pick of tank loot.

4. On caster items, +hit gear goes to DPS casters first, and +critical strike gear goes to healing casters first.

We have no other rules beyond that.  The one we are considering is giving first pick rights to different melee classes based on which stats benefits them more, especially on accessories such as rings and trinkets that multiple classes can use - i.e. agility rings go to rogues before warriors.  That is a complicated one, especially for specs such as my main, where it's not agility vs. strength that is looked for, but, in logical terms, (agi OR str) AND stam.

We decided against using tools such as DKP because our guild does not want to completely discourage PUGs or guildmates that don't have very much time to raid from coming - if they don't have time to come 2 nights a week, that's ok, they'll still have their shots at gearing up.

We're a pretty mature group in general, almost always willing to help each other out, and that helps - we have regulars that will step out to let folks that don't get a chance to go every week have a turn, and folks that are willing to pass on items that are small upgrades for themselves to let others get much bigger upgrades.

So... is this kinda normal, or are we way out in left field?