both are crap. I used to have xfire 6850's about a week ago, microstuttering and inconsistent fps is terrible with them. Its probably ok if you havnt seen a decent single card, but after a month of using them i was fed up. got a gtx660 2gb and will never look back. And the extra vram of newer cards really helps with some newer games. If i were you i would sell your 5770's and aim for a 2gb 7870, 7850 or gtx660 depending on your budget, and you will realise what it is to have a smooth gaming experience. Charts do not show what is happening, crossfire will lead to low dips in fps and gameplay that is not smooth. Single card is the way to go unless you need more than what the fastest single card can provide you, like for triple monitor or above 1080p gaming.
Yeah, you're right. This is my first gaming rig, and i've only used crossfire 5770's from the start. I know what micro-stuttering is technically - however, in the games I've played (mainly bf3, a little bit o skyrim), i haven't felt it - or you could say I don't know if its happening or not due to the fact that I've never experienced it before. I got both of the cards new for 80$ together.
Thanks for the advice. I was tempted into buying the 6850's crossfired, but you've changed my mind.