I've had mostly good experiences with KEH over the years. The only times I've sold equipment to them has beenduring their "live, in-person buying events" at local camera stores. They give you a quote on the spot and if you accept, they write you a check right there.
The only offers I didn't accept from them were for my film equipment because it was way too low. As for all the digital equipment I've sold them, their prices have been somewhat low but fair.
Also, the gear I've sold them in the past has always been in either LN- or EX+ condition (all in original boxes). As some of you know me by now, I collect a ton of gear from different brands and end up disliking most of it. I'm seriously considering selling off my Sony A7iv and a few Canon RF lenses I dislike sometime soon at one of their next in-person buying events. Not sure though.
I’ve had trouble too and don’t use them. In my case they held it 30 days. They did step down a grade (fine) but slashed the offer by like 20%. Not because of the grade, everything marked down. But I got my stuff back correctly…
Ironically enough if you share a story like that I got much the same response here. Oh well.