I turned off upnp on the router at slingbox locale and it forced a relay mode when used with iPad or iPhone and it seems much better. Data rate stays pegged at 3400kbps most of the time and tcp mode used to roller coaster from 200 to 8000.
Tcp mode seems way less stable even though it is supposed to be preferred setup method . My 350 is about 1400 miles away and maybe it's a excessive router hop issue. Some people have complained about RELAY mode but it's fine for me.
Also.. I have heard that RELAY mode relays the image to AWS (Amazon Web Services) and maybe I get less router hops... Or the relay doesn't allow Comcast to throttle port 5201. Or.. the smart people at Amazon have a better buffering algorithm versus TCP connection.
Either way I'm happier... I'm realistic and realize that a few dropouts have to be expected. But I was getting WAY more dropouts during prime time hours at night. Sometimes I couldn't even get connected again.
Hope this helps somebody.