I think the biggest thing for me was that I didn't know that a convex bevel was "allowed", and it never crossed my mind to try it. I had pretty much resigned myself to either having to buy a grinder, using my jig, or spending a whole lot of time using less sharp chisels as I learned to freehand them. I spent a ton of time reading on the internet, read all the sharpening books I could find, and watched all the videos I could find as well. This is the first sharpening method that has done everything I want, and it does it quickly and gets things very sharp, so I'm happy. I'm glad you guys are happy with your methods too!
I'm not sure about the effective difference between secondary bevels and the convex bevel. For me though, sharpening in a convex bevel gives me a very easily repeatable action that I couldn't get the hang of with a secondary bevel. I would always second guess myself on the angles, and found moving back and forth keeping on the same plane without a hollow grind quite difficult.
I also think there is something to the stropping involved, since by putting pressure on the center of the convex bevel the leather seems to compress in the shape of the bevel and polish it all at the same time. Kind of pointless to have the back half super highly polished, but I haven't had the same problems dubbing the edge over as I used to.
Anyways, I doubt any of it really matters much when the blade hits the wood. Main difference seems to be whether you use a grinder or not.