A good SnD player does both, knows when to rush and sit back and which maps allow for rushing or not. I do both regularly get 10-15 kills no problem by utilising both tactics.
well maybe not 15 but true (at least not every game)
Depending on the competition, camping wins.
Rush will get you a couple of kills sometimes, but a camper with a sniper or m16 could easily take you out.