I have one - the 18Ah model, since it was on sale through Woot.com for half price a while back. I haven't used it all that much, but it came in extremely handy when I had it with me and forgot my laptop power supply, but had the cord to use the power pack with my laptop. I've also got the little add-on gizmo that lets one charge smaller lithium cells from a USB port like the one on my model (though it's far cheaper to get it from DealExtreme -
SKU#15624.
I do wish they'd given a little more technical detail; unfortunately the case is pretty thoroughly sealed and I didn't want to ruin it just to have a peek inside and see what the actual battery arrangement is. Clearly there's voltage regulation going on; I suspect that the battery pack's native voltage is the high-voltage port, and it's down-regulated for the 5v USB and the other "low voltage" port, but I have no proof of this. It just seems unlikely that they'd use a voltage booster, but stranger things have happened.
I do find their act that they provide tips "for free" and you're just paying for shipping to be eyeroll inducing... marketers obviously know a lot of people love the word "free" even when it makes no sense. I guess I'd starve as a marketer because my approach would be to simply say "register your XPal and you get discounted tips for all your gear." Whether one's paying for the tip and getting free shipping or getting a free tip that one pays the shipping for - it boils down to the fact that the tips are quite reasonably priced. I also like the fact that they guarantee they'll find a tip for your gear.
The only downside I can think of is cosmetic; the smooth "piano black" cover is a fingerprint magnet, and I'd prefer a matte/textured finish but that obviously doesn't affect how well it works.
Frankly, I find it amazing to have 18 amp-hours in something the size of a paperback book - and not ridiculously heavy, at that.
