As for your questions, I still used a 300 Fatebringer in the raid and did work so a max TDYK would still wreck in my opinion. Depending on how much the level cap is raised, I think 300 damage would still be relevant. As for the new ones sold by the vendors, the vanguard one you can buy sucks with a 5 round mag, if you can get one with field scout from RNG then you got something to work with it. As for the one sold by the crucible, I'd say it's definitely worth it. I also would recommend getting a Thorn 2.0 from the bounty. It wrecks in PvE maxed out.