Mariesalias - regardless whether or not you have story progression on the game will still at least add sims it needs for community lots - co-workers- bosses- friends for your sims kids, which means at least a sim kids and 1 or 2 parents, possibly a family. Depends on what they game has in the pool for NPCs. So you cannot totally control the number of sims the game adds as it is required in the programming. Story Progression mainly makes the NPCs act like real folks in your hood without you having to control them all - it is not going to limit the program calls for sims or increase it - that is all in the programming. I would never advise to run the game without SP of some kind unless it is a really small world myself for many reasons.
