Yeah, the tap supports 5 players.  Each controller has a switch above the D-Pad with positions 1-5 marked.  I may see if the wife wants to play bonk 3 or bomberman to try out the multiplayer aspect.
The line of sight isn't too bad.  30 degrees of vertical range, and 70 degrees of horizontal (lateral) range.  I sit about 6-7 feet from the tap, so the distance opens up the range a lot.  I could see if I were sitting close to the unit where the range could be annoying, but then why would I need a cordless remote?
I'm really pleased with the controller itself too.  No lag, no choppy transmitting, and they don't weigh four pounds.  They are solid controllers.
I highly recommend them, if you have the means.