I was looking at the one's listed as Odessey which are $334ea. Looks like the 10% discount is still available, so that would put it at $600 for those batteries. The X2Power are $300 ea - 10%, so $540 for the pair. Not sure if there's shipping on that or not, but its still some serious coin to drop for a pair of batteries. I can understand where it would be needed in some applications though.
I like the idea of them being a drop in solution, but I can get Group 31s for around $100 ea, and for the $300+ difference in price, I'm willing to make a few mods. I've cranked and cranked and cranked on my 31's and never had a problem. If I crank so long that I start to loose some power, something else has gone noticeably wrong. If I had other high current needs, I'd be willing to spend the money, but just for starting the truck, I can't justify it. A good Group 31 will give me 950CCA ea. Not as much reserve as a deep cycle, but I've cranked on mine long enough to have killed at least 2 sets of Group 59s, and they still had plenty of life in them.