I don't know how they are over speed bumps, check my ride height! I must go slow all the time over them, sideways.
As for dilatation joints, cracks, etc. Very well.
Listen, you must understand that ANY shock/springs or coilovers WILL BE STIFFER than stock. The main difference is how well the shock is built. The more quality shock you have, to more insane spring rate you can run without having a bone-crushing ride.
In example: I took a ride in a GR STi equipped with all the bars, sways, links you can imagine, plus a set of 12/10 KW Clubsport coilovers. Man, those was terrific! About as comfy as my current R3 (6/3)!!!! Of course I can talk about suspension types, geometry and all, but this is to give you an idea.