As an owner and player of the current Descent, I'm thrilled to hear about the 2nd edition of Descent and the upgrade pack. While we loved the theme, concept, and general playing of Descent, but we no longer play it for one MAJOR reason, and one I beg you not to repeat in 2e. Simply put, the rules in descent are a mess!! They are vague, don't cover all situations, don't work correctly, or simply make for poor play. Worst of all, the infrequent FAQs released usually never fully addressed the problems or created new ones.
I also own FFG's Runewars, by Corey Konieczka. Do everyone a favor and follow the FANTASTIC work done with the Runewars rules, playtesting, and the follow ups on the low number of problems found with that game. We play Runewars because we like the game, but we continue playing it because the rues work and are clean and cover all situations. We like Descent but we don't play it because of the rules are vague, broken, unbalanced, and are just ... bad.
In short, make sure the rules are solid and playtest it (and the rules!!!) as much as you've done with Runewars. Lastly, any chance Cory is on the D2 team?