I've noticed a difference in shard rates, but not in magic attack power/potency. I tried out the dual combo of ice and lightning, and couldn't tell any difference in resist rates or number boosts. However, once I went even across the board with my elemental stats, i'm literally overloaded with shards (and getting a LOT more crystals too) of every kind. Mobs and harvesting both have been much better about dropping 3 or 4 types, and between 3-6 of each kind now.
Jerri Blank (Strangers with Candy):
"I may still be doing all the wrong things, but now i'm doing them the right way!"