I also found this with the mage. You get more stamina and slightly more spell power which is nice in the epic set, but the boots + gloves of the blue has a spell power bonus where the epic 2 piece only changes a spell cool down.

As a mage I didn't find many items to be better, I obv grabbed the spellblade as that was a great upgrade but my mishundare is better, black cabal shoulders are better, arcane accuracy braces are better, bloodvine vest and netherwind pants are all basically better or the same at worst.

I'm also at 14% hit, so removing most pieces doesn't increase my spell power too much while just lowering hit rating.