The way I've always seen it fluff wise, yes the elves spend a few hundred years mastering their magic, I've always felt the humans laughed at them a bit for taking so damn long! I guess I see elves as patient and willing to take their time, humans just want to get stuck in and blow stuff up.
If I was writing the rules to reflect this fluff, I'd make HE take a ld test when they rolled IF/miscast. If they pass, the spell is cast as normal, if they fail then follow the normal IF/miscast rules. Empire wizards on the other hand should have 'double 1 = miscast' rule. Point cost each properly and I think it'd fit well!
. . . Sorry about off topic :P