My Thoughts on Built to Last
I like the sort of options that built to last opens up with item centered builds, however the problem I've always had with the perk in both implementations is how it restricts your choice of items to only items with high charge counts.
This naturally is because of the percentage of charges nature of the perk in both states, and creates some pretty gnarly things with the perk like commodious toolbox + charge add-ons + streetwise + built to last. But then if you brought a mechanics tool box you get roughly one third of the value from this set up despite being in the same item rarity and supposedly?
I would ask you test a version of Built to Last that refills a flat number of charges as opposed to a percentage number, say 16 so you could run this perk with brown med kits and yellow toolboxes and get a more consistent value out of it when compared to commodious toolbox or ranger medkit.