i agree stronger as a whole...
but if each part is designed to be its own ship they would be strong
ie: design a ship then have it added to another part.
to clarify : a ship that combines rather than separates world be strong as a separated ship and stronger as a combined ship.
also imagine if starfleet had had 40 combined starships against the borg that would (depending on number of parts) be a lot more ships... with two parts thats 80 ships, with 4 parts that's 160 ships ;)