I have a Catalyst version myself. It's the first printing and the most out of date. There is some newer artwork and included errata in the Posthuman Studios edition so pick that up if you have the option but some stores are marking down the Catalyst print due to time passed. If you can get a Catalyst print at a discount then go for it, just make sure to download the errata linked above.

This probably doesn't matter much, but I found out where the book says what printing it is. For the core rule book, it should be on page 5 on the middle right side of the page. I have files for both the second and third printing of the core rule book (which are consistent with the above statement), but not the first printing (so I can't verify if that printing is also consistent). For the other books, they seem to keep the printing or version info in a similar location, just after the table of contents. The adventures don't seem to have table of contents, but they seem to keep the information on the first page that isn't the cover. The adventure "Glory" breaks this pattern by keeping the information on the last page.

Is there a list of the changes and erratas between printing somewhere; please? I think I have the 3 versions or at least 1st and 3rd; and would like to see (easierly than by comparing text to text) how the rules evolved as it is interesting from a gameplay perspective.