From my understanding the following will be doing live streams:
G4
GameTrailers
IGN
Gamespot
All I can really think of so with that said which one will you be using to use the E3 conferences on? For me it will be Gametrailers because I always use them when it comes to trailers. I also assume the servers are pretty darn strong there due to how big the site is and the traffic which it gets. Will watch on GT and keep Gaf and this site open for any meltdowns. :D