I've seen both ways of handling stacked shearwall panels, however the strap method would make more sense from an economic standpoint:
The main point here is that you have either option at your disposal with the new shearwall module.
Notice the inclusion of the top plate clips on the lower shearwall and the 16d Common fasteners in the sole plate of the upper shearwall. Both of these items are optional however if that degree of detail is required or desired it is also readily available to the designer or engineer.
See model here:
https://3dwarehouse.sketchup.com/model/3cedfba5-baaf-4e8a-8b36-0357c630b6d3/Shearwalls-2
The main point here is that you have either option at your disposal with the new shearwall module.
Notice the inclusion of the top plate clips on the lower shearwall and the 16d Common fasteners in the sole plate of the upper shearwall. Both of these items are optional however if that degree of detail is required or desired it is also readily available to the designer or engineer.
See model here:
https://3dwarehouse.sketchup.com/model/3cedfba5-baaf-4e8a-8b36-0357c630b6d3/Shearwalls-2