Hi Matthias15,
The GMAT is a remarkably consistent and predictable Exam; the last major change was back in 2012 (when the IR section replaced the Issue Essay). The materials, concepts, patterns, logic, etc. in the AWA, Quant and Verbal sections are all essentially the same though, so it sounds like the term 'recent' is being used in relative terms. There is so much available, "recent" material that you really shouldn't have to use anything that's 'too old' (anything that predates 2010, for example) - but to answer your immediate concern - the GMAC material is all high quality, relevant material, so you can (and should) use those resources.
GMAT assassins aren't born, they're made,
Rich