IMHO, hiding the SSID in the top 5 things that would grab a hacker's attention. It literally screams "I have something to hide and I don't want anyone on my network." Sure the average user won't see it on Windows "Wireless Networks" list, however Windows is still aware of the "hidden" AP because it can see the MAC address of the beacon.
Building on that MAC filtering is easily hackable
especially if encryption is off - also on my top 5 list. All I need is one packet and about two minutes to clone that mac to my NIC, reboot, and voila, I'm now your computer (from the DIR-655's perspective).
In terms of performance, it has been shown the 655 is [/i]faster[/i] when in G/N mode with WPA/WPA2 enabled. If I could find which D-Link employee said it in the fourm, I would quote it.
From a security perspective MAC filtering should really be used as an "enforcer" of encryption. For example if you ask your kids not to share the wireless password with their friends, would they
really listen to you? The way to enforce it is even if they do get the encryption password, the MAC address wouldn't be in the allowed table. Of course if they have the wireless password, if you had really smart kids, they too could clone the MAC address. MAC filtering is very, very weak.
I could see where it would be stronger with the Guest Zone (which is a VLAN) and only if routing between zones is disabled. They wouldn't be able to sniff traffic from the primary zone and gather those mac addresses. There would have to be at least one approved client in the guest zone for that hack to work if the attacker knew the wireless password.