I've flown these mods, and the various STOL kits on 182s, and most other Cessnas. VGs are low cost, and noticeably beneficial, with one caveat; if you're going to get snow on the wings, VGs make it about impossible to wipe off, without wiping a few of them off too. Similarly, VGs don't react well to wing covers. So, VG's are best for always hangared, or summer climate airplanes, but worth it, if those are your prevailing conditions.
I've et up and flown a number of AoA systems. Dating back to the [non electronic] "Lift Reserve Indicator" of the 1970's, and recently including several Alpha Systems AoAs on Cessnas and a Siai Marchetti 1019. They work. However, there is an error in the set up instructions which I discovered a year ago, and discussed in great detail with the manufacturer. I found the error while setting one up on a Cessna T206H with VG's and wing extensions. The result of the error was that it was not possible to calibrate it down to the actual stall speed of the plane, and still have a safe normal power off approach speed. It was fine for a factory configuration plane (which it is intended for), but once you start mixing it with wing mods, it is very complicated to calibrate for set up. That said, I flew 100 hours in the 182 amphibian with Sportsman STOL, wing extensions and the Alpha Systems AoA. When flying very precise landings, it was always eyes out, and fly by feel, so I never referred to the AoA system. AoA's are great for higher performance planes, when maneuvering. My experience has been for short runway work, I just did not go eyes in to look at it. Anticipating this, in the 182 amphibian, I installed the display well ahead on the glare shield, so it was sort of eyes out, but I still did not refer to it much. On the T206H I set up last spring, the display was a heads up type, which was magnificent.
The bottom line is that for the really tight operations, practice is your best tool. With lots of practice, you'll find that supplemental information is not as important.
In this video I'm landing into a nice lake in Norway. The AOA indicator can be seen on the glareshield. Though it's flashing on the video, it is steady in operation, the flashing is the video camera, not the indicator.
This is a very short (for an amphibian) runway landing I did in Norway. I didn't use the AoA at all for this landing, I was totally focused eyes out. Though it's not the really short landings which can be achieved with wheel 182's, for a heavy amphib, it's short. I did the calculations, and had 15 more meters of runway available than the ground roll portion of the performance charts stated for the day. I was demonstrating the plane for the owner (after which I made him promise that he would not land it there!)