I'd go Helu if it's PPR.
Dallas's run D is decent, but shutting down Frank Gore (eight in the box, Alex Smith) and Shonn Greene (just not that good) is about as much of an accomplishment as Tennessee's pass defense shutting down Luke McCown and Joe Flacco.
Miles Austin is out, Felix Jones is out, Romo is so banged up that he's sleeping in a chair because laying down hurts too much, and Dez Bryant is questionable. There's a better than average chance Dallas's offense struggles, and a good chance Romo doesn't finish the game. You put Jon Kitna in with Jesse Holley as his top receiver and it isn't going to be pretty.
Washington is probably going to have the ball alot in this game, and Helu should get at least 10-15 total touches, 3-5 of which will be catches.