I am just a homeowner who believes in researching before buying. I was ready to pull the trigger on either the Cub Cadet SC 100 or Troy-Bilt TB110 until I saw the molded plastic piece that holds the handles onto the mower and the rubber flap on the rear bottom. It is the same on the SC 500z and self propelled models in the other brand lines made by the same company. It is on Craftsman, Troy-Bilt, MTD, and probably every other brand they make. There is a bolt that goes through the handle and has a nut on the other end, there is a plastic knob on top that turns and tightens it against the plastic pieces Even when tight you get some flex on the handle and if you try to really crank it down the plastic pieces to the left and right that you are tightening against start to bend. If you go to the following website and look at the third row down and last picture on the right and click on it to enlarge it you will see the area I am referring to. I looked at it real close in person and this is a deal breaker for me. Husqvarna, Toro and Honda make mowers with some kind of a metal bracket that attaches the handle to the mower so I will go for one of those brands. These pictures are from the exact mower you mentioned.
https://www.google.com/search?q=sc+...:en-US:official&client=firefox-a&channel=fflb
Another review of the mower you are looking at.
The Best Walk-Behind Lawnmowers: Comparison Test - Popular Mechanics