my main is a shadow tank named Jaberse on the Ebon Hawk. i can show you what a shadow tank should look like lol.
they have the highest mitigation potential as well as the single greatest CD on around a 31 second cool down in fights where your getting hit rapidly. although our armour is lowest out of the tanking classes we more than make up for it in mitigation stats. fully min maxed (before Dreadguard gear) im sitting at a 40.25% damage reduction 33.33% defence chance (which in all honesty, ive never seen anyone with higher in this stat) 66% shield chance (W/ kinetic ward) and a 60% absorbtion sitting at just shy of 25K HP.
all of this combined with a great defensive panic button on a very short cooldown make us incredibly versatile because although we may take a good deal of damage from force and tech attacks we can trn all that damage to 0 by one quick keystroke or mouse click. on top of everything we have the largest amount of consistent self healing (not absolutely positive on that so don't quote me).
in no way am i talking down the guardian, the guardian played very well and a shadow played very well are probably pretty damn close to equal and are suited for different tasks.
shadows make great main tanks and guardians make excelent off tanks for all their temps and "oh ****" buttons.
optimally if i were running a raid. i would prefer to have a guardian tank with me over any else.
I agree that a Guardian & Shadow combo is the best tanking set up although I'd swap the Guardian in as MT and have the Shadow OT. Recent content however pretty much destroys the MT/OT distinction thanks to multiple bosses and repeated tank swaps.
In terms of your 33.33% Defense chance: stock Rakata Guardian gear has close to 40% Defense but needs to be itemized down.
In terms of CDs: Shadow have the best situationally useful CD in the game. Guardians have the best Universally useful ones. Enure is also better than Battle Readiness and Adrenalin Surge if you have a healer.