I used the roller type and it wasn't easy, the fender wants to flex since there is nothing stopping it from bowing out. The fender appears to be double layer anywhere that there is a tab for adding fender trim so I had to bend that with a rubber/poly mallet.
Looks like a good DIY idea but I think my forearms would be worn out after on fender with the new tool, only clamps ~1-2" at a time. I would think you would still need to heat the lip with a heat gun so the paint doesn't crack when you crimp it also so you'd have to keep heating it a lot as it would take a few minutes to crimp each time, by then the next piece will have cooled.
Jon