AirDisk vs Shared Disk

yes

In contrast the above reply, the answer most certainly ought to be it depends on your setup. I'm seeing much slower speeds than direct attached. It depends.
-Deva

I've done extensive testing, and can get around 3.5Mbps sustained write to an AirDisk. Conversely, I can get the max of around 10.35Mbps If I mount the same volume attached to my iMac from my MacBook.

Curiously, there appears to be some software kinks, as it should be at least as fast writing to the AirDisk. MacIntTouch Reader Reports detailed this issue, showing that write speeds to an AirDisk start high then drop considerably, and never return higher.

I haven't re-done this test after installing the new Airport Update (2007-02).

Read speeds seemed even in the two setups. I used Activity Monitor to find out the average/maximum transfer speed.

Additionally, it should be noted that I've also chosen the shared disk method for the ability to spin down the drive when not in use, it seemed that my AE didn't do it, and after reading some threads, I strongly feel Apple needs to include some sort of software setting that would let you choose the spindown time.

In each case, I was using an 802.11n - only Dual Channel connection, with the iMac wired into the Airport Extreme and the MacBook (Core2Duo 2Ghz) wirelessly connected, about 25 feet away, through a concrete wall.

In reality USB2 is slower then direct connect of drives.
Direct connect G5 Dual 2.3 with internal RAID sending data to a Maxtor One Touch III

39 Megabytes per second with Firewire 800
28 Megabytes per second with Firewire 400
9 Megabyes per second with USB2

I now have an AirPort Extreme N with the drive connected via USB2 now

Wireless connect from Dell E1505 with internal 7200RPM drive sending to network drive (Maxtor One Touch III) connected to the AirPort backing up using Retrospect (EMC Insignia)

60 Megabytes per minute with wireless
1 Megabyte per second with wireless
See related article at www.barefeats.com/usb2.html

Note about Airport Extreme:
After running the AirPort Extreme Disk, I found that I could not see the drive on one of my laptops. When I entered the password it would generate an error and not connect. It turns out that McAfee Security works fine but Norton Firewall had a problem. You have to set a range that is considered secure in the exceptions. That range is the DHCP range your AirPort Extreme generates. Default is 10.0.1.1 to 10.0.1.200. If you enter that range into the firewall as secure, you can then use the USB Hard Drive you have connected to your AirPort Extreme.

Some backup applications require a UNC path to recognize the network drive. Go to “My Network Places” in the “Start Menu” and right click on the icon the represents your network drive connected to your AirPort Extreme. The UNC path will be something like this “ \\AirPortExtreme\network 100”.

Using Retrospect http://www.emcinsignia.com/solutions/overview/dataprotection/
From EMC Insignia allows me to backup my Macintosh G5, Dell E1505, Del D610 and Gateway Laptops all to the same network USB2 drive I have connected to my AirPort Extreme. This is very cool and very easy. Just remember in setup that you have to put in the UNC path for the network drive.

Using iTunes on my G5 and Windows Laptops, I can stream music to my AirPort Express connected to my home stereo system with sound quality that rivals hard wire connections. I can not tell the difference on my Rotel Amplified, B&W Speakers connected to my computer via cable or wirelessly via the AirPort Express. The Linksys is garbage and not a good product. Now all Mac and Windows systems can play music on the home stereo.

Sorry, Misread the question. (no excuse, I'm just tired).