Pros: Standard drop in for P60 host. I have many lights from DX. The main reason I get all these lights just because they are very affordable! I read and did so much research on lights lately just want to find out how far LED technology has gone. After extensive search and comparison, finally I found the best. Look no further.

Cons: Currently R5 is the most efficient LED available for drop in. That may be the reason this light doesn't heat up or may be the reflector doesn't dissipate heat from the LED.
I just worried if poor heat dissipation will kill/shortern the LED life.

Other Thoughts: The color temperature of R5 is kinda warmth since it's a little yellowish. No big deal, as long as it's really bright.
Lights pattern: white center surrounded by yellowish ring.
I noticed at Mid and Low, the driver produce high frequency sound. However it's barely noticeable unless you bring it very close to your ear.

Bottomline: If you own a P60 host this will be the best drop in at this price. If don't have P60 host, don't worry, there are couple P60 hosts at reasonable price. I suggest you get sku:14885 charger, sku:20392 18650 battery, sku:16240 P60 host for 43bucks.

Pros: If you are browsing this drop-in, you know it's the brightest available in its class. After comparing to P7 C and D-bins, this drop-in matches performance at 1A what the P7s throw at 2A.
With both lights operating (at the above rates), the area one expects to have lit by vehicle headlights is lit perfectly by this module. The P7 does fill in the sides much better, and on a bike they really complement one another.
However, given the heat and charge cycle issues from running the P7 at 2A means that in reality, the P7 can't operate for as long as many poeple will need the light. I did a sag test with http://www.dealextreme.com/details.dx/sku.19624 cells and got 2:15 till it switched automatically to strobe mode.
In this host: http://www.dealextreme.com/details.dx/sku.16241 heat dissipation was fine, though 1A is not difficult to deal with.

Cons: There really are no pitfalls to this SKU. The light pulls 1A at any voltage up to 8.2 (where I ended my tests), and starts to drop slightly when the cell sags to ~3.7, though not that bad. I'll run it again and get more data on late sag.
The only way to improve this would be a boost mode added, but at this price, come on!
This light has no cons unless you refuse to pay its price. That is your call.

Other Thoughts: This R5 emitter in a P60 drop-in should be the best selling emitter package. For all of the hype of the quad-die emitters, this amazing LED has crept in with efficiency that really does offer a powerful counter-point to the less efficient P7s.
By the time you factor in heat and cell sag, any application where the LED is operating for more than 20 minutes or so is going to wish they had this over any of the quad-die emitters. If you have a well-ventilated light with 2 or more high capacity cells (18mm at least) then you can get some benefit, all others really need to buy one of these modules. Not only is it the best in class, it can also be retro-fitted to replace some earlier emitters (rather than upgrading to a P7 torch).
I really only bought this just to test throw against the P7s I had purchased for bike light and similar applications. I'm ordering another right now, and some drivers to see how well it runs at 1.2A.

Bottomline: If you have any qualms about a P7 or similar emitter, you absolutely should get this instead. There are going to be so many people with buyer's remorse who get the P7s not knowing its caveats.
If you recommend a light / emitter for high power in a compact (single 18650 cell) light for a newb, it's really best to point to this.
let the user decide to get the P7 only when they understand the qualifiers. I think it's a mistake to hype the P7s when the same performance is available with less power consumption, and the power consumption on small lights can be a deal breaker, not to mention a heart-breaker when your fancy light melts.

Pros: 1. Has broken the barrier between adaquate drop-in and capable, serious drop-in.
2. Reasonable price.
3. Large input voltage range.
4. Multi level illumination.

Cons: 1. Strobe is a bit slow to use on a firearm.
2. To many modes to use on a firearm (to many switches to get to strobe).
3. Can't use primary lithium cells.

Other Thoughts: I would like to see this drop-in configured as High > Strobe > Low.
I currently use sku.21037 MC-E in a SolarForce L2m on my pistol. I'd like to use this, but there are too many switch presses to get to the inadaquately slow strobe, and I can't use primary cells as backup.
See my photo comparison.

Bottomline: Great drop-in for the price. If you're considering getting one, don't hesitate.