hmmm, depends on the day. I honestly dont think it will be super busy at 6am BUT on Mondays there tends to be early week business travellers heading out so keep that in mind.
Once, we were running behind at Buffalo airport and there was a very long line at security. I went up to the accessibility line and asked if we could be pushed through as we were really behind for our gate and they did it.
BUF is awesome, I love flying from there.