Hey, All:
Sorry I'm late getting back into this thread. I spent most of this week on the production of Season 9 of "The Best Defense," so my plate was full...
With regard to the other questions asked:
Yojimbo 2 vs. Ronin 2: It's funny that the "R&D" for the original Ronin 2 consisted of my friend Mickey Yurco literally tracing a Yojimbo 2 on a piece of paper and making me a fixed blade version. When I asked Spyderco if it was OK for Mickey to make a few, they graciously agreed. When I took delivery on a few from Mickey at the Blade Show, they were very impressed and snagged one to put in the prototype case. Customer feedback was good and the rest is history.
The primary difference between the two is, of course, the difference between fixed-blade and folder, which basically translates into ease of carry, speed of draw, and legality. If you can legally carry either one, the fixed blade is faster and easier to draw, but less convenient. If your local laws don't allow fixed blades, the Yo 2 is obviously a better choice.
On a side note, the laws in Colorado do allow fixed blades; however, I opt to carry Yojimbo 2s instead because I travel so often and have to play by other states' rules on a regular basis. I don't want to have to change gears every other week to switch back and forth between the two deployment skill sets.
Also, even though I designed the Yo 2 to be Colorado legal, when it was adapted to the Ronin 2 and the scales were shortened to accommodate the sheath function, the blade functionally got longer and is now no longer Colorado legal. As such, just as I've custom ground a few "Chicagojimbos" to fit Chicago's 2.5-inch blade length limit, I've also ground a few "ColoRonins" for the same reason.
As for my thoughts on the PPT and Fred's designs, I LOVE THEM! Long before I met Fred, I was a big fan of his work. Now that we've been good friends for a number of years and had the opportunity to discuss blade design, tactics, and many other topics at length, my respect for him and his down-to-earth approach is even greater. Although some of his designs, like the Street Beat and Street Bowie, still have more belly than I prefer, the PPT's straighter edge and lower point is significantly more Wharncliffy without sacrificing tip strength. It's hybrid blend of a "scaled Reeve Integral Lock" is also an underappreciated element of brilliance that provides the lock strength of a RIL without the problems associated with touching the lock bar while trying to open the knife one handed (i.e. pushing the detent ball deeper and fouling your opening).
On another side note, I wrote an article on Fred for Blade last year and another for FMG. In them, I explained that my favorite design of his--and my favorite neck knife period--is his Neck Bowie. Fred appreciated the articles and to express his thanks made me a custom Wharncliffe Neck Bowie. I promptly shared it on social media and Fred was bombarded with requests for one. To meet that need, he, with Spyderco's blessing, had the design produced by his mid-tech maker, Max Knives. It's called the Fusion and it is now my new absolute favorite small fixed blade/neck knife.
Again, thank you all for a cool thread and for your interest in my "take" on things...
Stay safe,
Mike