Sorry to hear your cables are too short HardyWeinberg. I second your praise of the Minewt X2 Dual. I Just got my set today and it is bright! I ride a Downtube 8H and it fits perfectly. Actually, and this might sound strange, but the cable seems too long on my bike! The light is a lot smaller than I expected. The little lights themselves are each about the size of a golf-ball made into a tapered rectangular shape. Brightness is very good for my purposes.
I'm starting to commute by bike and ride mostly near street lights, which render the Minewt X2 just a "be-seen" light. For the portions of my commute that are dark trail and low-lit street where I need to see, the light works well. The strobe effect is a very intense effect. The only major con I can think of with the Minewt X2 dual is the battery life and lighting while cornering. I would prefer to have a little more battery life, thinking into the future for any bike tours or more extended night riding, but for now the Minewt X2 dual suits me just fine. For what it's worth, I lucked out on a good Performance coupon day and ended up getting the thing for $174.
Other lights I tried out before I settled on the Minewt X2 Dual is a Dual Halogen set up (20W + 10W) (I forget the brand), the Planet Bike Beamer 5 (bright but very tight spot, I would recommend this light for city riding under a lot of street lights), and the Planet Bike Super Spot (I wasn't too impressed with this light). These other lights had drawbacks, such as not bright enough, didn't have enough spill, got too hot, etc.
Where are you guys experiencing O-ring breakage? Is it just the quality of the rubber that make them snap or any adverse movements I should avoid? Is adjusting them "on-the-fly" a problem, i.e., moving the lights slightly up or down when attached on the handlebar?