Using an addon that returns character stats to readable format I've come to this regarding pvp stats on a Feral Druid:
> Using an int weapon reduces damage significantly;
> Using int on other gear doesn't have effect on my stats at all.
So if I have a ilevel 700 pvp trinket with agi and a ilevel 710 pvp trinket with int, 710 is better; But that does not apply to weapons. Weapon has to have your stat type to remain effective.
The addon is called DejaCharacterStats, so you can test for yourself whether your class s affected by equipping various things before BG starts and seeing if your dmg / spell power shifts for better or worse.