It is functional, but not the best design. The upgrade kit makes it better.

The problem is that stock system doesn't have a lot of resistance to the crossbar rotating around the axis parallel to the width of the boat. It can rotate that way if you pull or push hard on the tiller. If the crossbar rotates, the pins connecting the crossbar to the tiller arms are no longer straight up and down, which binds the whole system.

With the stock system you can try to avoid this problem by torquing the connectors to the tiller arms harder (make sure the bolt has the little sleeve around it so you don't crush the tiller arm). Or get the upgraded connectors that don't rely on friction to resist rotation in the wrong axis.