I have never purchased anything from KEH, but I have sold a few lenses to them. They have been a very reputable outfit whenever I have dealt with them.
Yeah, think I may have bought a used MF lens or two (probably Nikon macro lenses) from KEH before -- forget now. They definitely seem to be one of the (biggest and) most reputable dealers for used photo gear and are listed as Nikon authorized dealer. They also do repairs w/ Nikon parts (although I thought I came across some quib that indicated Nikon might no longer provide them parts now). When I asked them on Amazon marketplace (about the refurbed D800), they told me they might opt to do the repairs themselves after the 90-day Nikon refurb warranty expires w/in their own 1-year warranty period for refurbs -- they normally offer 180-day warranty for used items. So that's probably better than typical offers for refurbed gear, which makes the ~$150 diff (from the other eBay option I considered) even more marginal as a factor.
So I'm just gonna order the refurbed D800 from KEH via eBay now before my eBay coupon expires tonight. Doubt I'll get a better deal for a refurbed D800 for the forseeable future...
Thanks again, y'all, for all the input on this purchase...