Actually, scratch that. I remembered that I have my syn-level set to subject line only for privacy (through obscurity, yes) reasons, but I crosspost full entries between DW and LJ. I wouldn't want to either crosspost only subject lines to LJ or send my full entries out on the general RSS feed. So am changing my vote. I think that the ability to crosspost only partial entries to other LJ-type sites would be useful, but it shouldn't be tied to the RSS syn level. And there could be a default setting for it, but I would also think it would be good to be able to override the default for individual entries.