If you get there as early as you say, it shouldn't be an issue, but if you look at the map, you will see that Lot 6 doesn't necessarily get you closer to the stadium than day-of-game parking in Lot 7P. It is a comfort though knowing that if you happen to run late, there will be a spot waiting for you. And almost always, you will then be allowed to park in any of the lots (even those that may require an additional donation amount) since the folks that direct you where to park have already been let go.
Since you asked about extra space to tailgate, I've often purchased an extra pass that allows us to have an empty space next to us for more room. I think it's more of a benefit to those that get there really early as you most likely will be parking next to others that plan on staying in the lot to tailgate. Unfortunately with the changes made to the tickets and parking last year, I'm now limited to only two parking passes and one of those I give to a fellow season ticket holder so we no longer have the extra space. Last year we were very fortunate that it seemed like there were always cars next to us with people who parked and walked immediately to the stadium or somewhere else.