Adding more cone washers (called Bellville washers, probably from the name of original patent holder long ago) to a stack of such washers lengthens the stack but lowers the spring constant, that is, the rate at which force builds with motion. The force versus distance curve has a lower slope.
However, In a fixed length location, the additional springs also take up more space, so all the spring washers are compressed more than previously. This results in a higher spring force when the larger number of springs are pushed into the same space.
The individual cone washers have a non-linear force versus displacement curve. To know what the old force was and what the new force will be with the new washers added requires a technical catalog showing the force versus displacement curve for this particular spring washer. With that and the dimensions of the spring stack and the length of the stack when the pin is extended one can easily calculate the force before and after. I guess one has to ask Lancair what the length is for the spring stack shown in the drawing with pin extended. Then the analysis can be completed.
I suspect it is difficult to come up with a coil spring that fits in the same space that exerts the desired force. Spring washers are a good solution to this problem. Perhaps more important is the slope of the angled tip of the pin. I suspect that this has a greater impact on ability to push the spring back than modest changes in spring force. And then there is the question of the hardness of the pin and the shaft against which it is resting. Lots to consider.
Fred Moreno