There have been two consequences of this forum shift, I've neglected my LJ contacts, and I've gotten hooked on the daily receipt of "kudos" and comments from new readers on Archive. I don't think either of these effects are positive. I write for myself, but it would be untruthful to say that the enthusiasm of readers doesn't matter, and being reminded that others are touched by what I take time to craft is wonderful. But the substantive discussions that can be had on LJ don't emerge on Archive.
That said, I think Archive is a great example of the advocacy of writers for writers, and I recommend it to others. It isn't a journaling tool. I like the networking on LJ and the ability to connect with my writer friends around the world without the creepy aspects of Facebook. Despite the limitations on time, I think both LJ and Archive are worthy tools.