Personally I'm aiming at getting the Sony unit in the near future,
couple of reasons really,, the slingbox has a range of 3000 miles, sony appears not to have a restriction.
The sony unit has built in wireless, the slingbox you need to get a wireless adapter unit to with it,,, added cost!
I believe the slingbox has a built in tuner though,, and the Sony has to rely on whatever inputs!
All round though, I think the sony is the better option!