As I have no option to test drive workbenches in different heights before I build my own my plan is to build the workbench top first. Then I place it on sturdy sawhorses and place some 2x4s between to adjust to different heights. I hope that this will give me some insight to what lenght my legs should be when finished.

Using Chris Schwarz rule of thumb for me seems a bit to low. I think my back will take more punishment than it will save my arms. As I understand it that is Chris thought behind using a lower bench – to reduce the work performed by your arms, transfering that load to the legs.

There is also the strategy to use a removable moxon twin screw vise that you clamp to your benchtop when sawing dovetails and other tasks that needs to come up a bit. See this article for some more info on that: Declaring Victory with the Double-screw Vise