ddt4free-- are you sure that the TZ-75 is a Sig clone? I own a CZ-75B and just handled a TZ-75 at a pawn shop yesterday. It was marked as "TZ-75" and was for all intents and purposes the same shape and width as my 1996 CZ-75. In fact, the fit and finish were every bit as good as my CZ. The gun had walnut grips and the back strap had a bit more significant curve to it but otherwise the feel was exactly the same as the CZ.
I have never been a fan of Witness' Wonderfinish (to me it just looks like somebody forgot to wipe off the cosmoline protectant for the trip across the ocean), and as far as the two guns go, having held the Witness next to the CZ when I was trying to decide which one to buy last year, there was hands down no comparison between the Witness and the CZ--I bought the CZ without a second's hesitation.
Had the choice been between the CZ and the TZ that I held yesterday, I don't think the decision would have been nearly as clearly cut.
I bought the CZ and a year later am completely thrilled with the gun--it's my favorite range gun. Accurate, easy re-coil, never jams, great weight, durable finish.
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Triggers exist to be pulled... again and again.