You have 4 dogs already?
What breeds and what ages and what sexes?
What experience have you had with large working breeds? Have you taken your other dogs to obedience classes? Are you prepared to take a new dog to classes?
I would be reluctant to bring in a new pup be it Shepherd or Rottweiler into a home that has so many dogs already. Both breeds need alot of training and time...and with 4 dogs getting alot of the attention I would be worried about a pup getting enough training and attention to grow into a well balanced dog.
Gina