Just finished my initial testing on the target dummies in Theramore, using Arcane, Fire and Frost specs @70 on live. Toon is 5/8 T6 geared, not a lot of Sunwell loot. Testing was done hit capped for each spec (17% without talents, or very close to it) altering gear.
Arcane rotation was ABar, ABla, Miss Barr on procs (arcane power used on each test)
Arc/Fire rotation was ABar, FB, Mis Barr on procs (arcane power used on each test after 1st Mis Barr proc)
Fire rotation (with scorch glyph) was scorch (till stacked), FB, Instant Pyro on procs (combustion used on each test)
Frost rotation was frostbolt, instant FB on procs (water elemental used once on each test)
Molten fury and water elemental timing will vary on boss fights of varying length of course. DPS was calculated by using a stopwatch and using Recount to capture total damage done (results were close to recount's dps calc).
Certainly not a statistically perfect set of tests, but eight tests with each spec yielded the following results:
Fire (13/48/00, Molten Armor) 1501 dps (Std Dev 177), oom in 100s (Std Dev 17s)
Frost (00/00/61, Molten Armor) 1419 dps (Std Dev 80), oom in 112s (Std Dev 7s)
Arc/Fire (52/09/00, Mage Armor) 1400 dps (Std Dev 129), oom in 73s (Std Dev 6s)
Arcane (58/03/00, Mage Armor) 1298 dps (Std Dev 34), oom in 116s (Std Dev 25s)
To see the general level of gear used:
The World of Warcraft Armory
Bottom line, frost was 5.5% behind fire, arc/fire was 6.8% behind and arcane was 13.5% behind. Fire went oom 13.3% faster than arcane, and frost just 2.9% faster than arcane. I was surprised that Arc/Fire (with mage armor and mage armor glyph just added) went oom 37% faster than Arcane spec and was the worst performing when it comes to mana by far.
Of course, YMMV.
(edited to include Arc/Fire 52/09/00 spec).