riojazz
If I understand the problem correctly, the tip is not quite this:  "Do NOT run USB-powered external gear on your DAW".  The tip is to connect an external power supply when you use such equipment (when possible).
 

FWIW, I have two external drives connected (via USB) to my DAW but they are not power sourced until I need them. Been using them that way for over a year now.
 
No problems that I know of.
 
Same is true of my laptop (which I run SONAR on from time to time).

I haven't tried HDs yet, but others who have reported the same issue seem to consistently see it with keyboard/controllers. Power consumption difference, maybe?

I checked and found that my A-500 Pro is pulling 500ma of USB power. I think this is the design max for USB and my quad capture is also running 500 ma.
 
I too am going to explore wall warts. If you do buy a power supply make sure the current rating in milliamps is high enough, and make extra sure that the polarity is correct. Some have positive on the center pin and some are negative. Good quality devices usually have protection built in but some will just blow up (figuratively).

My USB MIDI controllers both use USB power. I haven't noticed any difference between when they are turned on or not. I did however invest in a 700W Coolermaster Pro power supply and a pretty high end ASUS MOBO (which I plug the devices directly into... not the front of the case) so maybe that helps. Maybe not. My controllers are a Korg padKontrol and an M-Audio Oxygen 25 in case anyone was curious. Maybe they just aren't power hogs. I read that it's best to keep your PSU at 500W or more for heavy duty usage like a DAW but I forget where and I have no idea if that's true... but I heeded that warning anyway. The Coolermaster has been pretty awesome BTW.
 
My USB interface uses a wall wart though which is supposedly better than one that does not. Again... can't remember where I read that but it makes sense.