It's easy to get it to post to multiple journals at once, but my experience is that Semagic has no idea what to do with the access/subscription split. Unless it's been updated since I was messing about with it last year, you cannot manage your circle with Semagic and the posts to DW are not properly filtered (if you chose to filter them). Also, it can't read/use all the post metadata that DW uses (and sometimes this behaved in odd ways, like, I couldn't even pick a mood, which is common, unlike the adult-flagging which obviously works differently on DW vs LJ).

I gave up Semagic and I haven't been pleased with any of the minimal (IMO) efforts towards clients that some DW users have made. I just got used to the web interface from DW, even though usually I prefer client-type programs for this purpose.