I wonder these things
there's a few test videos floating around when XS was testing. Basically the better batteries will maintain a higher voltage under load and last longer. Virgin lead vs. recycled lead accounts for some of the differences according to XS.
You also have to look at the short circuit ratings, the cca's and the AH's.
Here is a stupid question... where are these mystical blemish deka's at??
I have used kinetiks, stingers, dekas, c&d's, etc... And they all have held up just fine no matter how much strain I put on them, Im at the point to where I look for the most battery for my dollar...
i noticed a significant difference going from my dekas (which were very well maintained) to my 3100's. how quickly the battery can deliver the potential it has stored makes a big difference.
Where do you get them?
AH is a crapfest of a spec to look at, I tend to look at Cranking Amps. Cranking amps are the numbers of amperes a lead-acid battery at 32 degrees F (0 degrees C) can deliver for 30 seconds and maintain at least 1.2 volts per cell, which is typical for our application.
There's an interesting unbiased deka vs xs test on floridaspl. IMO for a daily set up deka is the way to go, haven't seen anything "magical" from xs set ups to justify the ridiculous prices...