The 2.3mil stretch goal is my favorite so far, because I'm an Infinity Engine junkie and mastered all of the hardest BG/IWD challenges (mods included) on the highest difficulty. I *really* enjoy RTWP combat of yore and am very okay with fiddling around the same combat situation dozens of times until I get it right.
Now... I will probably cry many tears because I won't be able to resist ticking all of the +difficulty checkmarks right off the bat. I'm the "challenge for the sake of challenge" person those options likely are intended for,
BUT... How about attaching a 5% experience bonus to each of the game modes? It's not a straight up "You're missing out if you're not doing this" kind of thing, but it's an added incentive to face challenges one might otherwise not and surely preferable to the notion of giving people better equipment for playing a certain way. This is highly egotistical, since, as I said, I'll check Expert/Path of the Damned/Iron Man anyway, but 15% more EXP would make it SO much more rewarding.