Nah, to me, Invasion clearly has a Spartan bias. Spartans get lasers, rocket launchers, sniper rifles, a hog and a scorpion, as well as shotgun and 'nade launcher spawns.

Elites have their power weapons (Fusion Rifle and Plasma Launcher) spawn right in the middle of the old Spartan base when the Spartans are still in there. Their Ghost/'shee/Wraith are all laser/launcher/scorpion fodder, and they get what, Sword spawns? Fantastic, easily countered by the shotgun. If push comes to shove, the Spartans can camp that final room with shotguns and rocket launchers and there's smurf all the Elites can do.

If you own the Spartans hard on Invasion then you are probably playing against a bunch of incompetent people to be honest.

Not that I care, more often than not I am a Spartan anyway and I enjoy absolutely raping the alien bastards

EDIT: If you want proof Spartans are better, I looked at my last 20 games of Invasion, and Spartans won 17 times, Elites won 3. And the 3 are the oldest 3 games, when presumably people still didn't know what they were doing. Enough smurfing said.