To be fair I dropped an Audi A4 down around 40mm and it was only speed humps that caused issues. Unfortunately our roads are not like billiard table tops, more like a replication of the cratered surface from the moon...
In regards to the original questions, I've had cars in the past with
coilovers and
lowering springs. Personally I found them both to be a hard ride, but the
lowering springs were slightly more forgiving.