Oh for God's sake.
The signing out thing is never seriously used. In my first year I'd spend nights away from college a couple of times a week, and I never once signed out. The only time they tell you off for not signing out is if they have a fire drill (about which we are usually warned beforehand, so it's easy to just sign out that night, to avoid problems.)
If you don't like signing in guests, opt to live on Iffley Road, like me.
The Norrington Table doesn't show everything. It doesn't say anything about the happiness of its students, or the quality of the food, or the architecture or the room size or any of the other factors that add to a student's enjoyment of life in a college. Just because someone is at a college at the bottom of the Norrington Table, that doesn't mean they themselves are necessarily less likely to get a first, for example. If you put the work in, it doesn't matter who your tutors are or what libraries you have access to. And Hilda's doesn't even have a "perennial position at the bottom of the Norrington Table". Like Hobnob said, Oriel has been consistently near the bottom for the past few years, below Hilda's, and it doesn't get any flack for it.
I've lived in Hilda's for two and a half years now. The people there are amazing. Yes, some of the rules are strict, but if you get to know the porters then they're also rather flexible. Yes, there aren't any boys there. But you're still part of a mixed university. Hardly any of my teaching is in college, or single sex. I have groups of friends both within my own college and in other colleges.
I wille be interested to see what happens when the guys come next year. Less so what happens to the atmosphere within college (I like it now, I also like mixed colleges, so I doubt I'll have a problem with the new situation) but rather what happens to the college's reputation. So much of it is based on the fact that we're clearly all hideous brain-dead lesbians. The stereotypes of other colleges aren't taken so literally, or actually believed (Welsh sheep-shaggers at Jesus, boring farts at Merton etc etc).