I've owned the PD20 (Q5 version) for about 8 months. Here are my feelings:
PROS:
• Very small, even for a single-CR123 light. Bezel diameter is just a hair over 20mm, and the entire length of the light is about 80mm. Plus there is an even narrower part in the middle for a very secure and comfortable cigar-hold (proper term?).
• Pretty throwy with a tight hot spot, yet decent spill.
• Anti-roll design.
• Easy UI, with just the right amount of modes and outputs.
CONS:
• Don't like reverse clickies. But that's what you get with Fenix.
• No clip. I don't even know if anyone makes a clip that would fit the PD20 Q5.
• The beam profile is a little ringy.
• Mine has a tiny piece of something stuck to the side of the emitter that shows up as a little dark artifact (proper term?) when shining up close on a wall.
• Non-removable head. I could maybe fix the above problem if I could get to it.
All in all, I like this little light, and would recommend it to anyone looking for a relatively inexpensive, pocket-thrower with a pretty good UI.