Elites in Invasion Slayer have such a big advantage. Played two matches with Elites and three with Spartans and I never won once while playing as the Spartans and I won the two matches while playing as the Elites. With Elites, it's so damn easy it's not even funny. The loadouts aren't really great for Spartans at the beginning so I think that's the reason why. What I've seen most of the time is that Elites get around 20 kills before the second armor loadouts appear, then the Spartans usually never keep up in scores because we either have one or two Ghosts. Also: energy sword + stalker = cheap cheap cheap!!! 
It's the other way around in Invasion though. Spartans are just too good. Only once did the Elites pass through the first round when I was playing as Spartans.
I guess it's the first time we see the two species battle it out against each other with the armor abilities involved. It was fun playing Elites Vs Elites, but Spartans Vs Elites is slightly unbalanced right now from what I've seen. I know Bungie won't disappoint and the fans will give them good feedback. Just fix the balance and how the spawn points are handled in Invasion and I'll be happy (also maybe fixing the loadouts in the first round for Spartans in Invasion Slayer would make the games a bit more interesting).
And to anyone that is interested, that's what I wrote a few games before: http://www.vgchartz.com/forum/post.php?post=3391256&page=3&postnum=27
Random game thought :
Why is Bionic Commando Rearmed 2 getting so much hate? We finally get a real game and they're not even satisfied... I'm starting to hate the gaming community so f****** much...
