G43 are hitting the streets now. Our store has been getting a few a week, but they would usually disappear in hours. Once, I got one for long enough so I could compare it with G42. Initially, I thought that though the slide is obviously larger and the frame is obviously slightly longer at the muzzle, the rest of the frame is just the same. When they sit side by side, they do look very similar!
But then I got the micrometer, and in fact all the dimensions of G43 are slightly larger than that of G42:
The beauty is in the eyes of the beholder, of course, but it feels like G42 is more height-weight proportional, and G43 looks a bit "overweight".