There was a simaler thread on Gixerjunkies years ago, someone who was a machinist took a pazzo a standard lever and one of these to work and tested them by cutting through the lever and carrying out various metel stress tests.
He found there was a difference but it was so small it wouldn't make any difference in the use of the lever as the metal was 99.9% the same. And both the pazzo and Chinese lever were better metal than the standard one.
He also said that even if he took two pazzo levers from different batches there would be just about the same difference.
I had pazzos on my k4 gsxr and when you put the two levers side by side there are slight differences mainly with the nut and span lever, but in isolation you'd be hard pressed to tell the difference unlessnyou knew what to look for.
And for the saving of over £100 a set
I've had two sets of these since then and they have been great even took a crash at Donnington and didn't break.
I would have no reservation in getting another set.