Hmm, WHATEVER!! All good mail spell power gear basically has crit AND haste on it, so you don't have to worry about it. Sure it's nice to be able to choose what you want more, but mostly you KNOW when an item is a clear upgrade over the other. Basically though, if you are wondering about gems, go +hit until you get capped. Hit rating is cheaper than crit and haste and is a flat increase, 1% hit rating is 1% dps, 1% crit or haste is not necessarily 1% dps.

I can see the argument though that haste is almost useles suntil you get enough to be able to squeeze in an extra lb before lvb comes off cd. Because if you are casting while it comes off cd, that's time wasted that could be spent casting lvb as it's the highest dps spell. What you want is a rotation that will your cast end at the exact moment lvb comes off cd so you can cast it straight away. It makes sense imo.