1. Add additional tiers to the challenges. Many of them top out after tier two which is unlocked really early on. Additional tiers would be great especially if they included purple gear. There's some gear that require 50 purples to craft this would go a long way towards alleviating the grind of the gear system.
2. Consider rotating gear offered on a weekly basis. I have a large stockpile of the gear offered from the challenges and some lower level gear that I'm always farming for. A rotation would be nice to see.
I appreciate the inclusion of the Mk 4 SoroSuub Keypad and the inclusion of the once a week ability to do all challenges in one day. Those have both been very helpful.