Mastery and Shadow Damage

Hi folks,
Just thought I'd throw out a question for some help. Currently, Im 3/8 Heroic raiding on my DK and Ive noticed my damage stagnating at a place Im not happy with. I've done plenty of pouring over my own parses and those of the bottom-end rankers in this class. I guess what it boils down to is this.
Yes, EJ gives stat priority of Haste>Mastery with Gurth for us. But to what degree am I losing damage by not giving Mastery its own priority?
Currently Im at 2619 (20.45%) Haste but only 1108 (14.18) Mastery.
Any help would be much appreciated.
My understanding is mastery has it's own priority...It's just low.

TMK the stat weights of an Unholy DK don't have any synergy like that of an elemental shaman (The more haste we have the more chances our mastery can proc, the more mastery we have the stronger having haste becomes). Therefore it's going to boil down to a lot of straightforward math. Which stat gives the best DPS? Stat X? Ok, stack it. What gives the least amount of DPS? Stat Y? Ok, avoid it like the plague then. If you sacrifice stat X for stat Y you have less of X which gives more dps than Y.

The only time I could imagine sacrificing haste for mastery is if you wanted to stay at a haste breakpoint, and even then I'd imagine having faster rune regeneration to outweigh that, although I could be wrong about that. In my light reading of Unholy it sounds like there are 2 breakpoints that exist with UF and your ghoul/Gargoyle.

I could be wrong since I'm just dipping my toes into Unholy now (Was frost until I got gurth), and I don't play this DK much.
Make sure to empty all your RP and pop AMS during magic heavy sections. this will allow you to spam DC for a short amount of time. Best of all the runic corruption's buff time stacks.