Well, my initial comment would be that while it's a cool idea, it's severely lacking in implementation. There are significant quantities of information that the sheet doesn't take as inputs (for instance, any statistics about one's offhand weapon, any mention of haste, armor penetration, or procs on gear, etc.) which means that it's going to be sort of doomed from the get-go in terms of producing accurate results.

The second problem is that it doesn't seem to adjust it's gear formula correctly by class; for instance, entering in my stats as a rogue, it tells me that the 2nd best helm in the game is Cowl of Beastly Rage, which is a terrible rogue item. Moreover, it says that the best available neck is Archaedic Shard, and the best available cloak is Thoriumweave. Clearly it's way overvaluing armor value for rogues.

For that matter, it recommends Pillar of Ferocity as a 2-Handed weapon, and the only 1H weapon it comes up with for me is The Unbreakable Will - neither of which precisely makes sense from a rogues point of view.

In terms of gemming, I note that it's using Swift Skyfire Diamond as the metagem recommendation for all helms, which is clearly and vastly inferior to both Relentless Earthstorm Diamond and Thundering Skyfire Diamond. It's also recommending Radiant Spencerite and TCHILTON TEST RUBY for all colored sockets, which has two problems:
a) neither of these actually exist, and
b) both are clearly inferior to other available options.

All in all - it needs a fair bit of work, i would argue.

I hadn't seen Alla's search in some time. Quite nice. Right off, I can say one thing Lootzor has over it - Lootzor tries to fit the best kind of gem into sockets, scoring the item accordingly. It'll even try to satisfy socket bonuses when possible, or ignore them if it can get a better deal that way. This saves a great deal of time, as with Alla, it seems I would have to weight "[color] socket" the same as the best gem I could find for it, and it still wouldn't account for socket bonuses.

Alla, by contrast, will let you weight more things than Lootzor does. The lack of haste support is admittedly annoying. Also annoying is Lootzor's lack of info for the sources of many items; it really comes across as a work in progress.

Yet another feature these searches lack is a way to assess the whole outfit together. I doubt Lootzor, for example, would weight a Spellfire Vest more highly than some alternative because it would break your set.

Somewhat related note: yes, I value spell hit slightly more than +dmg, but if I followed that weighting for every slot, I'd end up with around, oh, 455 more spell hit rating, which is silly. It'd be great if the search could tell me, "well, [Cowl of Insane Precision] is the best hat you can get, but if you use [Pants of Potency], that'll give you the +hit you require, while letting you use [Cowl of the Egomancer], which has slightly less +hit in return for a great deal more +dmg}. It'd -really- get the kudos if it could figure my spec choices in - "gem more +hit, and you can take that point from Elemental Precision and put it in Arcane Mind for better results". (Yes, I'm making a lot of this up.)

To be fair, of course, this would be an insane amount of logic to incorporate for nine classes, and for the moving target that is a character's loot acquisition status.

Spirit isn't great, but it certainly isn't worth zero. I mean, shamans don't have a Meditation-type talent, but it's not like they're exempt from the Five Second Rule mechanics either. Any time I haven't finished a spell in the last 5 seconds, I'm getting something out of spirit. I wouldn't actively seek it out given its budget if I could construct my ideal items, but it's definitely a nonzero value.

When you're giving a value to damage it really means just damage. Not "damage and healing."

So if you make +dam and +heal each worth 2 points, it thinks the +9dam gem is worth 36 (18 for the +9dam and 18 for the +9 heal) and the +14heal gem is worth 28 (14 healing x 2). If you are a healer and really just want healing gear, set +dam to 0.