Hmm, it depends on the level you are - and if you are asking for that, I don't think yo are that good with PU. My city is medium-sized too, but I don't even care for that now. I've approached some girls like three times, in a period of ~2-3 months and they see that I'm getting better and better. It's really fun when I meet them now - we're like friends - and yeah we even talk about picking up girls.
I have a few other examples, when I meet a girl I've approached and another that I haven't. Usually the first goes "Oh, I know you. You were that X guy." - and starts explaining about me to her friend. And then the other becomes really interested, and starts asking you questions...
I suppose there are downsides to all this, but I haven't discovered them yet.
But yeah, you may want to do your first approaches somewhere where you don't know anybody - I guess it helps you get rid of AA. But once you've past that level of the game, you don't have to worry.