Broadcom 4313? Yeah, the max speed is 72Mbps and due to that it's still classified as Wireless-N.
I have the same Wifi Card in my DV6 but other than the max speed, I never suffer any disconnection or weak signal.
Perhaps it's due to driver but it could also could be due to hardware design such as the antenna itself.
Perhaps those suffering from the Wi-Fi problem could use the driver from other laptop maker or the chipset maker.