That's a very good point you bring up.
I'm primarily concerned with the data transfer performance of my iMac which is physically connected to the AEBS via gigabit ethernet.
My iMac would see a doubling of the data transfer rate with the Firewire 800 network drive. USB 2.0 is a definite bottleneck here.
An ideal solution would be to use a hard drive with an ethernet interface since Apple provides several ethernet ports. Unfortunately there are numerous problems associated with that solution, such as a requirement for NAS network software which complies with Apple file naming conventions, compatibility with Time Machine, and $price since the drive would actually need to be a network server rather than a simple hard drive.
I have a MacBook Pro and I require that it have wireless access to the internet. It be should also be able to perform automatic wireless backups using Time Machine. I don't want to have to make physical connections. That's the rationale behind the Time Capsule. I would like to be able to duplicate that capability with AEBS without having to purchase a Time Capsule. I also need to occasionally transfer files from one computer to the other via the network drive; this task would be accelerated with a connection faster than USB.
Speedwise, the 802.11n draft max bit rate is 600 mbps @5GHz.
Tests show the AEBS 802.11n to be from 54 to 86 mbps @5GHz.
USB 2.0 is 480 mbps.
Firewire 800 is 800 mbps.
USB 2.0's maximum rate of 480 mbps is a burst rate which quickly subsides whereas Firewire's 400/800 mbps is a sustained data rate due to greater efficiency of the protocol.
Of course if Apple provided an eSATA port, throughput of 1200 mbps could be realized.
Your main point that the wireless connection is much slower than the hardware interface is correct. However as I have tried to point out there are additional performance considerations.
