Maybe a little off topic, but do you Tanks ever carry around multiple sets of Tank Gear? (or at least pieces that you swap in and out, maybe a different Relic, change a chest piece etc...)
I am a Damage Sponge - High Hit Point Pool for boss fights that hit hard, but really slow.
Avoidance Set - Multiple weak attacks, mainly Trash type stuff?
Threat Set - sacrifice some tanking stats for more DPS/Threat
I know when I played WoW and Raided, I had about 5 Tanks sets for the above plus for things like Elemental Damage type resistant Gear.
And in Rift I would even switch my spec out during Dungeons/Raids for specific fights as well (really loved my tank that could not be knocked back during a fight).
Or is it mostly just one Tank Spec, one Tank Set of Armour?
I do carry around different relics, however the latest round of content has me mostly using the dread guard on use relics.
The on use power relic used to be nice on fights where there was nothing to defend/shield but the changes to tank threat and the higher endurance on dread guard tank relics make this one kind of pointless.
I also carry around war hero relics but I find in EC the on use relics are a lot better. There is a lot of time in every fight where you are either not taking damage or are only taking force/tech attacks. This devalues the static stats of the war hero relics. EC has very predictable phases which makes it easy to take advantage of on use relics.
I personally don't like the absorb proc relic. It's nice, but shielding an attack is already like winning the lottery. Absorbing a little bit more of a relatively small hit doesn't do anything for me.
I will continue to replace each type of relic as they are upgraded to be ready for future content that might make them superior.
I don't keep multiple sets of tank gear. That would be very expensive to maintain and it would siphon gear or crafting materials from other people that need it. With the Tionese/Columi/Rakata tokens it was easier to create multiple sets because chances were good that no one could use it, but now everyone can use the tokens. Any extra gear usually goes to off-specs, alts, recruits. Plus a lot of gear gets reverse engineered even when people need it to better benefit the guild. The relics are a nice way to customize gear without spending a lot of credits.
As an assassin there is not really a lot of choice in spec. You might move a point or two around but it won't make much difference either way.