I used to resist new stuff like this but after resisting lj for ages before falling madly in love with it have decided to sign up to any that look interesting but make no commitment to stick with them if they don't grab me.

But yes, the logistics may get complicated, and paradoxically be easier with three: my lj, my lj-mirror-on-dreamwidth (I like the idea of a frequently updated backup), and a separate dreamwidth blog for dreamwidth specific stuff.