But I think a lot of give-and-take is required from...critter...and crittee for that type of discussion to happen: con critters can display the same sort of sensitivity authors have about their written words in a public space.

Exactly. Which is why I think the personal aspect (liking the person you crit for) is necessary.

And yeah, con crit shouldn't be for fixing fic; it should be for future fics. But I'm not sure I wholly agree that when a fic is posted, it's finished. One thing I like about fanfic is I feel like I can continually tinker with it, because there's nothing "official" about it, unlike published works etc.

Of course, this is coming from someone who has trouble finishing things, ever.