Effective gearing usage per situation

I am beginning to realize that for most of the standard content and really most of the 10 man stuff, I don't need to use my tank gear at all. My dps set is more than adequate thanks to the fact a lot of the key stats like agility and armor are relatively the same. They key mitigation I gain comes from talents, not so much gear. It is only in some Naxx-25 situations (hatefuls on Patchwerk for example), that I really need to strap on my gear with more defense, dodge, stamina, and expertise. Even then I think I could squeak by without it most of the time if the healers keep up. It's a blessing and a curse to be able to switch around gear for any situation. It just takes a LOT longer to fill out two sets of upgrades. Flexibility is nice, but not without a price.