Well, essentially what I'm looking for/proposing is like EquipCompare, but on a larger scale. Less of a comparison between what you're mousing over and what you're wearing, this would display in a tabular format ALL of -say- your chest items, then list each stat, resist and effect. It could organize by ascending/descending by numerical stats, etc. This gives you a clean display of all your gear of a type or all types and what they add to your gearset.
For instance, you could conpare your Thick Silithid, Nightslayer, Bloodfang, Polar Tunic and Frostsaber chest items. This would display them all at once, showing their stats. This would make it very easy to create gearsets that -at-a-glance have the best stats or resists for your needs.
For example, it might look like this:
Obviously it would also show item icons, have drop downs, etc, but I hope this illustrates what I'm suggesting. It alllows you to compare these all and find the best match for the gear you need.