Anecdotal evidence is anecdotal.
From my spreadsheet, using your gear (at 70), PvP power is coming out ahead per single gem. The more SP you have, the better PvP power gets, so the gap becomes bigger.
PvP power is adding anywhere from 5% (starsurge, to 10% (wrath/starfire) more damage per gem. Add the lot up and the difference is quite large.
That said, you're balance. Unless wowhead's information is bad, the base damage on your spells (and SP coefficients) are much more inline with what 90s will get from the same. PvP power might be better for pure damage, but int adds crit. Balance loves crit.
In BGs though, I've a feeling int will win out thanks to scaling (but again it'll probably be close, not much changed between 70 and 74 scaling for other classes). Cba to re-adjust my numbers to compensate though.