unfortunately the net result isn't _quite_ the same. because LJ doesn't allow any ownership of feeds, and also doesn't turn off the comments, people are free to comment on your feed account on LJ (many do, not knowing that one doesn't receive the comments), and you'll have no option to turn off the comments, nor to have them emailed to you.
feed vs crossposting
if you crosspost from DW, you can do either.