Spine tolerance is a term that refers to how consistant the spine is from arrow to arrow in a set. People with spine testers can check out the various arrows to see how consistent this is. So far as I know the only technical data that list this is Easton ACC's. The spine tolerance is listed at .005". That means that within a set of them the spine varies no more .005". I've asked some of the various manufacturers of all carbon arrows what their's is and always get the same answer. They tell me what the spine is supposed to be for a certain size arrow but not how much they vary within a set. The thing they do like to list is the straightness. There's a big deal made of arrows that are straight to .001". This doesn't tell me much because it's been ascertained by most Olympic shooters that people can't shoot well enough to tell the difference between .001 and .003". So if straightness is your criteria for choosing an arrow then why pay the extra bucks to buy what you can't use? Of course there are other considerations we use when picking arrows, but frankly, from most people I run into it's mostly for bragging rights.
And if you really take a good look, most top of the line all carbons are just a couple bucks cheaper than ACC's. I already have the ACC's so why waste money on more arrows. I have used several AC's and have found that I break too many nocks and consequently split the arrows. This can be remedied by using Aluminum nock inserts and G-nocks.
Hope this info helpsyou some. Of course others will disagree but then we all don't shoot the same bow either.