Hi Justin
I'm sorry to hear you are leaving Pentax, but pleased you've decided on a brand that offers what you want.
I suspect you'll get a lot of responses challenging some of your reasons and statements, but you're a smart guy and I'm sure you'd expect nothing less considering the brand-specific nature of these forums. So, if some of the responses you receive are, to a greater or lesser extent, defensive of the brand, I trust you'll understand.
Personally, I love my Pentax gear, and it does more-or-less everything I want. That said, I don't have any pressing concerns over the resolving power of my lenses compared to my peers, or class-leading AF.C... This is just a hobby for me, and none of my images are going to be displayed on a wall at art gallery sizes. Come to think of it, I don't think I have any peers
I do wish that Ricoh Imaging would step up the pace in developing new glass for full frame, even though that doesn't affect me personally (since I'm sticking with APS-C for my Pentax gear). I think folks who've invested in the K-1 and K-1II deserve faster progress to maturity in the modern full-frame lens range. For this reason, I hope Ricoh Imaging reps read your post.
That said, many folks are very happy that they can use what they already have. Many still aspire to owning the "three princesses"... So it's very much down to the individual users needs and expectations.
I won't get into the problems you've had with AF or other aspects of technical performance. I acknowledge you and other folks have had them. I've had a few AF.C issues myself, but for my use cases, nothing I can't accept or work around. Again, I think it's down to the individual user as to how significant, intrusive and - hence - important these issues are. But there's room for improvement, sure.
In closing, I wish you the best of luck with Nikon and hope you won't be a stranger to these forums simply because of a brand change. It's just not that big of a deal... I think some folks take brand loyalty rather too seriously. Not me.. These cameras and lenses are all just tools. What works for one member won't work for another, for a variety of reasons. It's all good. What's important is that you find something you like, something that works for you, and get out there shooting.
Have fun, and don't be a stranger