At 50 ft you're playing with fire, especially with 1080p. I see now you can buy (RAM has them) amplified HDMI cables. There's a 20m amplified cable, guaranteed for 1080p, for $265. I'd do something like that or fiber, or cat5, and never worry about length vs resolution vs various differences in xmitters/recvrs again. If you are running cables through walls repeaters can be problematic. They should be "in the middle".
Ich bin hier und du bist mein Sofa