Its the extra damage % for high tier weapons that has been mentioned which is what is causing much frenzy. Some perks when enhanced are good and worth using, while non enhanced are not even really a consideration. Most though are an incremental upgrade, and are nice but not really needed. However, multiple bumps in stats across barrels/mags, enhanced perks and origin traits, could see a more substantial bump in performance from the same exact roll of low tier. Some of the timer bumps for damage perks are just enough to allow more forgiveness with its gameplay loop, but generally are not game breaking. The differences in Adept or standard weapons now, for the most part does not really change much. Other than the few weapons which can really take advantage of certain adept mods which are not available to normal weapons like charge or draw time to name two. We honestly dont know enough about the full scope of the weapon tier system to really know how it scales, other than the talk about extra damage for the higher tier (which would essentially allow you to spec into abilities instead of weapons and have the same damage, or spec into weapons and gain even more weapon damage due to how damage buffs apply multiplicatively.