Any Performance Disadvantages to this Wireless Setup?

The Setup:
Airport Extreme v7.4.2
Wireless Mode -- Create a wireless network
Wireless Network Name -- ABC (example only)
Radio Mode -- Automatic -- 802.11a/n - 802.11b/g/n
Radio Channel Selection -- Automatic
Wireless Security -- WPA/WPA2 Personal
5GHz Network Name -- ABC (5GHz) (example only)
Multicast Rate -- Low
Transmit Power -- 100%
WPA Group Key Timeout -- 1 hour
Use Wide Channels -- checked to enable

I do use MAC address filtering for additional security but do allow the broadcast of the network names.

The Hardware connected to the Airport Extreme:
iMac -- Ethernet
Macbook Pro -- network ABC (5GHZ) / 802.11 N
Macbook -- network ABC (5GHz) / 802.11 N
360 -- network ABC (5GHz) / 802.11 A
iPod Touches -- network ABC / 802.11 G
PS3 -- network ABC / 802.11 G
Lacie D2 1T hard drive USB
Cable Modem (no telephone connection)

Just wondering if this is the correct setup for my hardware that needs to connect to the router or if there is a better (increased performance) way to go.

Should the setup be revised if I make the following changes?
1. Change the 360 to 802.11 N by replacing it's wireless adaptor.
2. Add an AirPort Express to be connected to the PS3 by ethernet cable hopefully removing the PS3 as a 802.11 G device.
If I make these changes only the iPod Touches would not be capable of 802.11 N.

Long post I know but I appreciate your input.

Thanks