So far I’m keeping one of each legendary weapon while I get a feel for what’s good. At some point space will make that impractical, but for now, I’m keeping everything purple I can get my hands on. So it’s helpful to quickly see if I’ve already got one of something I just picked up, and then swap out and dismantle the lower power one (or use the higher power one to infuse something else).
I’m also working on a couple different sets of armor, which is almost purely for aesthetic reasons and not nearly as big a collection (there are some ugly styles I’m never going to bother collecting), but it’s helpful in the same way there.
DIM also recently added a UI feature where legendary gear that also has legendary mods has a gold border around it, which is very useful if you’re trying to remember what’s expendable and what you’ve already “invested” in with a mod.
And to clarify it’s not so much that I’m doing this outside of the game, but that while playing, I don’t have to go back to the tower or farm to access the vault. I can just find a safe corner wherever I am—in a mission, on patrols, etc.—and start moving stuff around.