i have the 676 for the living room and the 550 for the gameroom. In my experience, the 676 needs a more direct line of sight to work on any of my equipment. Sometimes it takes several button presses to get it to register what I want it to do, like turn up the volume or change the channel, which is frustrating. It also feels a little bulky and cheap, which is weird because it's way more expensive msrp wise than the 550.
But the 550 on the other hand I can point it in any direction, even away from my equipment and it still works. It typically registers what I'm trying to do on the first try. It's thinner, so to me it feels a little more high techy. I also like the blue lights it has. It works way better than the 676 does in my experience.
I would get the 550 over the 676 anyday.
