E-mailed GGROP an offline question regarding the “paper” sandwich core he’s referred to many times. He was kind enough to mail a sample to me and offer some insights to mull over, as well.
Turns out he was referring to CoreMat, which I’ve been aware of but not used, yet, for various reasons.
I’m aware that it’s intended for poly/vinyl-ester resin systems, in which you’re (in essence) creating a syntactic foam core when you saturate it with resin. But he threw me a bone and got me to consider another possibility by thinking “outside of the box”…
…when/if used with epoxies, the laminates not only bond to the CoreMat’s skins, but are then in turn bonded/pinned to each other through the perforation points in the material. In his words, “a poor mans’ honeycomb”!! 
Not tried this yet, and I think you’d have to use proper judgement in deciding on an appropriate application, but he’s definitely piqued my curiosity. Just thought I’d throw it out there…
Thanks, again!
Dutch