I started using magenuggets and combustionhelper to keep track.
I ended up giving up on mastery completely for fire, i went straight haste once i hit the 45% crit number with molten armor (because of the t3/t4 hotstreak ROI for crit). When we hit 85 mastery should be the best stat for fire hands down because we'll see our dots (including ffb) ticking for 200%+ damage.
Right now, it's basically useless except on adds.
In my testing with multiple targets in fire with mastery on the SW dummies (where combustion and LB spread to 2 other dummies because they are close together) I was pulling a sustained 13.5k on the dummies alone. In Ironforge with the single dummy it was around 9.5k, but when i dumped mastery and put it in haste it went to around 10.5k.
In arcane I can pull and maintain 11.5k on dummies self buffed, indefinitely, with spikes during cd's of over 20k dps....in ICC10 I'm averaging around 15k on single target fights in arcane, and similar in fire, but have some mastery reforges going on in arcane where I sacrificed some crit. It is weird being arcane and not running OOM, ever.
This week I'm testing arcane without extra mastery at all, just haste & crit for everything.