An 11 ms shock excites a natural frequency at 45 Hz while your Modal analysis recovered frequencies up to 577 Hz so that is plenty high enough.

It seems like all the materials stayed in the elastic range, so there is no need to have nonlinear material properties for this model.

One difference between a MSUP Transient and a full nonlinear Transient is when there is frictional contact in the model. Since Modal must convert nonlinear contacts into linear contact, frictional contact will behave differently in a MSUP Transient than a full Transient. For example, gaps cannot open up in a MSUP Transient in frictional contacts.