DW is originally based off the same codebase as LJ, though it's expanded a fair bit, and the transfer tools work pretty well. Plus, it's not like it wipes out the copy on LJ, so it's still here if something does go wrong (like enough people migrating at once that the LJ servers get overloaded or something.) It's pretty simple and well documented -- I did mine after one of the rounds of extreme flakitude from LJ.

If nothing else, it can be good to have an off-site backup.