I also have a few of his batteries and have sent many people his way. His communication is fantastic, his batteries perform as promised, I've never heard of anyone having a problem with one.
I've heard skepticism in regards to recelling batteries in general, nothing specific to him. I emailed him about it and he gave me a detailed explanation of why he believes there should be no concern. It didn't feel so much like a sales pitch either, more like objective information. Of course, that's the best sales pitch Despite Anton Bauer's amazing sale right now, I'm about to send John some HCs because I got a smoking deal and trust his recells to perform as new.