LJ is great for speedy updates and getting to know the authors. But I haven't yet found a way to say to LJ, "Hey, I have a hankering to read a bunch of Post-The Gift Spike fic. Please, make me cry." Plus, it's so much easier to find all the chapters of an older story consolidated in an archive.

Exactly. LJ is in fact incredibly inconvienient and annoying when it just comes to reading stories.

You have to do what will make you happy, of course. But I hope that if you do decide to give up the archive, you'll consider turning it over to someone else, if you can find someone you trust to take care of it. It is a thing of beauty.