B-ball & hockey are barely different without fans. Baseball is quite a bit different, but only when a visiting pitcher is in a jam.
Without fans, football will have the most pronounced difference of all the major sports. I think you'll see much higher scoring games in general, as road teams shouldn't have to spend any wasted time on hand signals and auto adjustments due to noise. Even for Bills road games, I doubt 3,000 fans in Miami will even create a din. Actually the 10,000 Bills fans in Miami may turn that one into a road game for the Fins.
That playoff crowd noise in Texas really hampered the Bills late in that game.