Thanks for mentioning my cutting board back in June.
Just wanted to let you know, I'm making a few revisions to the design - in my own using it, as noted in this thread, the mat was a bit too small to work as effectively as a larger plastic mat, and was too weak to be an effective scraper. The next iteration will have a slot for a standard 6" stainless bench scraper. Design as an iterative process...
I hear you on the slot being another avenue for moisture and weakens it slightly, but if the board is well-oiled and never submerged, it shouldn't be *that* much of a problem, especially for these boards that are 2" thick and for home use, but do hear where you're coming from. I wouldn't put a slot in a thinner board, tho, or in a professional-caliber board.
Fun stuff, these cutting boards. In my little niche, I'm focus on features that work well in small kitchens to make them easier to use, handle and store. In *lovely* Gowanus. More versions and features are on the way - and if any interest in custom boards or features, just give a shout.