From what I can tell, the load books are simply where some publisher has purchased test information from one or more labs and printed it in booklet form. This is also what Lee does to publish their manual, they simply do it on a bigger scale.
There is no telling how old this product is that the pamphlet printers are buying. Or, whether the pamphlet contains data from multiple sources. The only assumptions one can make at this point is that all the data was collected after 2005, and therefore represents data collected by the "safer" computer-assisted pressure transducer method rather than the older "copper unit" system.
One tell-tail sign might be the powders being listed. Accurate Sport Pistol and BE-86 are fairly new, but if all you're seeing in the booklet is standard powders from the 1990's like Bullseye, Unique, W231 then I would pass. That data is everywhere anyway.
Another big differentiator might be labeling. Do they simply say "Plated 124gr Bullet" or do they get into brand names ? There is a huge difference between Berry and X-treme bullet plating thicknesses and that would show up in the data. And there is a huge difference between the jacketed Hornady XTP and a JHP from (say for instance) RMR.
My personal opinion is that the booklets are a loss of time and money. But only because I already have a 3-ring binder. I can go to the Alliant, Accurate or Hodgdon powder sites and print anything I like, then punch it and place it in my binder. I keep several dozen pages in the 3-ring for new powders and bullets that haven't made it into the "big books" just yet. That system is quick, easy and free... and I know it is the latest info available.
I will also point out that if you ever order anything from Powder Valley, they are happy to throw in the printed load pamphlets from VihtaVuouri and other powder companies. All you have to do is add these zero cost items to your shopping cart at check out.
I may have danced all around the answer you were looking for, but I hope it helps.
