Defense Review posted an article about the Reset RIPR (Rifle Integrated Power Rail), and SSD and The Firearm Blog both briefly touched on the subject. So I though I'd toss up my first thoughts on the concept.
Right off the bat I'll just say it. I'm not a fan. At least not the current configuration. (Although I'm not really a huge fan of the concept in general either...)
The first problem in my mind, and the issue with the concept, is that you're putting all of your electronic eggs in one basket. You loose your battery power, and you don't just loose your red-dot. You loose your red-dot, flashlights, IR laser, iPod, and whatever else you have hooked on there. I feel you're much better off simply keeping a common battery type for all your devices (that's one of the reasons I run an EoTech XPS on my carbine, 123A batteries just like my white light.) It's nice to see DR agrees with that sentiment.
My other big issue is simply one with the current iteration of the system. It's adding bulk to the weapon as a trade off for one single battery, and it's a pretty big battery. The XPS is still the same size, just with an adapter plug jammed in the battery compartment (for all I know, can't see the other side to tell.) Add to that the proprietary rail that clamps on to your rail... I doubt you're saving any weight by cutting the standard batteries from your electronics.
The way I have Sigtyr set up right now I have 6 spare 123A batteries on board (in the Magpul ACS,) enough to swap out all the batteries in my electronics twice. I'm going to be out of ammo well before I'm out of power, and I don't have something the size and weight of a loaded 20 round mag leaching onto the side of my upper. I just have little sadle compartments on my stock that make for a kick-ass cheek weld.