I have half a dozen different original Giottos heads, from the first days of their import to the UK when we photographed and tested the product range. The importing company lost the franchise before we returned the gear, with the result that I had a full set of ball heads and their original circular quick change mount. In all cases, the heads have stood up well mechanically but - the tightening screw can come out entirely and get lost (same problem with Arca Swiss, my 1993 vintage Arca head has a replacement screw found from some other product); the rubber grips on the knobs loosen, then split, and fall off leaving the knobs bare metal.
Giottos products have come a long way in the last 10 years. These early ones are well engineered but not all that well designed, they just copied other makes and didn't know what problems would arise.