#25 - April 5, 2010, 5:33 p.m.
So... couple of thoughts here.
I think two difficulty modes work better when the following are true:
-- You don't need to do the normal version 100 times before doing the heroic version.
-- You aren't running both normal and heroic every week (or even 10 vs. 25 every week).
It feels more like a difficulty selection when the players who want an extra challenge can go hit that challenge right away. When you have to run the normal version a lot first, you just risk burning out faster, and you also learn the encounter specifics so well that by the time you hit heroics, the basics aren't a challenge any longer.