In my opinion The Spy 005 is an amazing flashlight.
The McLuxIII PD is a tool grade extreme condition resistant heavy duty flashlight and is also an amazing flashlight.
My Spy 005 is treated with more care by me than my PD. Not because it is any less durable or capable but because I consider the Spy 005 to be more of a dress light than a tool light.
I enjoy both flashlights very much. You really can't go wrong either way.
Since I have several Pd's I am a little biased to their favor. I EDC a U-Bin PD.
I do not EDC my spy. The SPY 005 would make a great EDC flashlight for the right person. It is not the right light for me to EDC.
In a way these lights to not stand up well to comparison.
They are completely and totally different in every way except for one thing The Beam produced is pretty much the same with the spy005 being slightly more floody.
The approach that these lights follow to produce light is very different. Just go to the FAQ's which are available for each light to find out what makes them so different.
Those same FAQ's will be a good source of information for you.
If I were in a position to be making this choice today? I wouldn't change a thing. Buy both. If faced with the "only one" choice it would have to be a McLux III PD. Simply because it lends itself more towards my style of carry than the Spy 005.
The Spy 005 is a fancy flashlight. The PD is more plain.
This whole answer is very mixed up and not crystal clear to me either.
Both are great. The best advice I can give is for you to determine what you need this light for. How will it be used. Then determine which light fits your planned use and mode of carry best.
Oh and one more thing. No matter which one you choose.. Go to
http://www.artofthehide.com/Holester.html and order a HOLESTER for your new light. You will not be able to find a better holster for either flashlight than you can from Matt.
He produces the best holsters for the best flashlights in the world.
Yaesumofo