I'm using a normal Slingbox and the 1st party slingbox app. It's actually fairly good quality. Not as good as say AirVideo was on the iPhone with streaming, but much better than Orb. I also think you can tweak the bitrate, but I only watch in short bouts on the phone. There is a delay, however, on commands. Basically, you'll press a command and it'll get sent, but the streaming will stop until the command is sent.
I'd assume that the app would work just fine with the Dish Network slingbox, but it is $30 for the app in store. As for the Dish Network end of things, that I dunno.