I have a Medford Arktika, Praetorian G, Praetorian T, and Viper. Let's do it like this:
KNIVES: I think they're awesome. I do construction and they get used. None have developed blade play, slop or stick. Solid as hell no problems whatsoever.
WARRANTY: haven't used it. Says he'll warranty it for life as long as you don't open it. I don't know man, just don't open it? I haven't, and seriously I never will. Why would I piss away a $750+ knife just to look inside it or try to fix it myself? As far as the cleaning thing goes, he just put a video up about it. Just rinse it in water, blow it out. He said it's packed with tetflon grease from airplane landing gear so it should keep crap out of the pivot. As far as knowing if you opened it, having a few of his knives I feel like they do things and make tiny marks on the knife hardware. Could be paranoia but knives having same marks on hardware is to coincidental for me.
GREG MEDFORD: I don't know him. All I know of him is from his youtube channel. What I get from him is that he is a very opinionated person that let's everyone know how he feels. If you agree with what he says you love him. If your views differ from his then you'll probably think he's nuts.
I also heard from my neighbors' barbers' garbage man that he donates alot to charity and does alot for veterans.
But since I didn't experience it myself I probably shouldn't talk about it, I could be spreading something that could be wrong, it is hearsay after all.
This is all my own opinion that probably means nothing to anyone lol. But I honestly tried to be unbiased.