First post here -- felt compelled to speak up.
I'm a former cartridge user that switched to DE safety razors just a couple of weeks ago, about 1 month after I started shaving my head. (It was time... Male pattern baldness had done its work years ago.)
Anyway, I used Mach 3 or Fusion mostly for my face for the last several years, and for a short while after I started head shaving, until I switched for a couple of weeks to the Head Blade. Then I (re)discovered safety razors and vintage safety razors in particular. I hadn't known these things even existed any longer.
Anyway, jumping ahead here. Just a few days ago, I gave the new Fusion with the "flex ball" a try because I had found a coupon for $6 off. I figured maybe I was missing out. So I bought one and gave it a try.
I *immediately* found that this razor, unlike the non-ball version, seemed to drag at odd angles and I had more cuts and irritation than I ever had before -- whether with a cartridge OR in my first attempts with a DE razor! I tried the older, non-ball version briefly for comparison and had normal results -- a close shave with no nicks or cuts.
I took the one I bought back to the store -- thinking maybe it was a quality control issue -- and exchanged it for another of the same kind. Had the same problem! Nicked myself several times before I skipped a day, then went back to using the old Fusion, then the head blade for two days until I healed up.
Long story short, and YMMV of course, but I hated my experience with the flex ball technology. Really hated it. I am now back to shaving with a vintage Gillette and a Schick Krona in rotation, or using the head blade occasionally if I am in a hurry on a given morning.
I suspect, for me, that it is a problem with the "gimbal" mechanics... After all, the way I think of it, by the time the blade needs to "pivot" to follow the topography of the face, it's really too late to make a difference for the blade, except to potentially pull that razor edge *off* line from the original angle. So instead of being in control of the oblique angle, the blade is moving independently of the stroke. At least that is my suspicion.
Whatever the real reason, I had the worst shave of my life with that torture device. If I had to either stop shaving altogether or shave just once more with the Flex Ball technology, I'd definitely quit shaving.
At best, I think it's a gimmick to allow Gillette to sell more proprietary blades at an even higher price point. At worst, I think it is an inherently flawed design that has been over-engineered and a complete waste of money.
So... There's my first post. A long one. But I felt strongly about this when I read the thread, and felt I should share my own view here. Take it FWIW. I have nothing to gain or lose by posting this... Just wanted to offer my own take.