Well, he wouldn't DH all the time...and I would expect his OPS to be more in the 790-820 range once you factor in the lefties.
The question I have is, can you get Morse for the same or less?
I will tell you this...if we could get Soriano for 2/10 and trade Avery or Hoes, along with a guy like Mike Wright, I probably would do that if nothing else was out there to be had at a reasonable price.
No, the Nats are looking for a good return on Morse, where Soriano is a straight salary dump.
I'd do it too, especially since odds are that none of those guys are going to be more than bench guys/BP arms. I wouldn't want him taking away AB from Reimold, because if he's healthy I think he might be the best bat on the team, and I would personally even look into moving Nolan to 1B in the spring to see if he has the hands for it, to try to keep him healthy, that would make Soriano as a LF/DH rotation with McLouth and Davis a pretty tempting option.