My bet is the router NAT function may drop the speed a bit. There are higher speed routers that your speed hounds may want. This is not an offer to research that area but you can look into faster routers. I am not talking about faster WiFi or Ethernet speeds but the router "processing" speed.
I have internet by Comcast: 50 Mega Bits Per Sec
Modem: Motorola SB6121 Surfboard
Router: NETGEAR N300 wireless router WNR200
The router I am using has a 10/100 Ethernet port, which connects to my computer that has a 10/100/1000 Ethernet port.
Can the 10/100 Ethernet port on the router fully utilize all the 50 Mega Bits? Or am I losing some speed due to the 10/100 Ethernet port.