You're fine, brother...ask, and I'll answer when I can. In this case, I have a few moments before I start my next build, so here goes:
First of all, the Smart Pwm v2.2 is not just a pwm board, its a specific board, a specific maker, basically the "brand name" of Voltrove Electronics. And it has features not normally found in pwm boards.
P-fet boards, if I'm not mistaken, are basically unregulated boards...unless, of course, its on a pwm board. I'm still kinda new and my biggest problem is that I'm not, in any way, versed in electronics. So I get lost in the language of electronics.
So, in essence, pwm boards can be adjusted through the potentiometer. And they pulse. And I'm guessing p-fet boards are constant, depending on battery capacity.
Next...I am not building any kinds of chargers in my mods and the reason for that, is balance charging is not that simple and it requires a little bit more components. So I charge my 18650s externally.
Next...sled mount and box mount.
Mostly preference, I would say. The sled mount is simple, easy and out of the way, but you are limited to that build. And, of course, the other option, you can do what you want. I, personally, like both, but when I mount my boards myself, I usually epoxy the board directly behind the 510 connector, completely out of the way and super clean looking. I had to try all the different styles and methods myself and will continue to do so. I recommend trying at least a couple of different methods, if finances allow it.
Next...from what I can gather, OKL and raptor boards are somewhat limited in wattage output, so that could be a deterrent...also, some of those boards can be a little bulky. Pwm boards have higher potential output and lots of them are tiny.
As far as Big Al's and the Smart Pwm v2.2...Big Al's board is a straight forward pwm board, no features. BUT, Big Al is coming out with a new board, the IPWM board, which will have features like the Smart Pwm v2.2.
I like both boards, I really do. But if I had to choose one over the other, than the Smart Pwm v2. 2 would be my choice and probably mostly for features like low voltage cutoff, on/off and, probably my favorite, voltage output lock...meaning you can lock your output voltage and the board will compensate for battery sag.
So, to wrap it up...get your fingers dirty, try things out, find what you like.
Note: Big Al's boards are easy to wire voltmeters to, so that's a plus!
Any other questions? Hit me!