I moved to a separate fic journal when I realised I was all over Google and I wanted a little privacy. In fact, I don't really use my regular journal enough to make the extra cost worthwhile, so I don't know whether I'll keep up with the two.

Advantages - having a separate fic journal makes it easier to find tags quickly.

Disadvantages - the icons I want to illustrate particular stories always seem to be in the wrong LJ. Also you need to keep track of which communities you're a member of on each.

But on the whole, I do like having both.