I didn't use Delicious as a fandom tool myself, but the loss of ff_press was a real blow. I noticed a real difference on the last FFXII story I posted to AO3 in terms of hit count. I might have to join a couple of communities and start cross-posting, just to feel connected again.

And definitely -- it would take a lot for me to give up my journal entirely. Tumblr is not at all suited for complex conversations or long, multi-thread discussions. Quick things, image based things, it's great, but not for real conversation, at least not that I've seen so far.