I know there is some confusion on the forums about how Easy, Normal, and Hard modes affect adventure stats, so I'm going to try and help clear that up. Those modes (Easy, Normal, and Hard) do not alter Magic Find, Gold Find, or XP Bonus in any way, and are just there so players can adjust the difficulty to their liking.
Once you're ready to handle something more challenging than Hard difficulty, however, those bonuses quickly ramp up. Here's what you can expect from Master I - Master V difficulties.
Master I: +60% Magic Find, +60% Gold Find, +120% XP Bonus
Master II: +70% Magic Find, +70% Gold Find, +140% XP Bonus
Master III: +80% Magic Find, +80% Gold Find, +160% XP Bonus
Master IV: +90% Magic Find, +90% Gold Find, +180% XP Bonus
Master V: +100% Magic Find, +100% Gold Find, +200% XP Bonus