Actually, I found my ISP bandwidth was the limiting factor over everything (768k upload speeds) and that 3g and 4g were fine for the bandwidth necessary for downloading to both my D1 and TB. That being said, I fine the picture is good enough, but the latency between commands (changing channels, dvr/etc) drives me a little crazy. Otherwise, the picture is great.
On another note, I have found the MLB live stream is excellent! I wish they had the same functionality as the PC (move to specific innings, pause, rewind, fastfoward), but I like to go to the gym and jump on the treadmill and watch the opening few innings of the Red Sox, and I have been extremely impressed wit the quality this year.
Last year I was sorely disappointed in just the MLB.tv pacage, as the DVR functionality and jumping to innings was horrible!
In any case, I would definitely give the slingbox a thumbs up. Now I'm just waiting for netflix to come to the android.