When I started my first job (40 employees) I saw it well done. There were two layers of management, but at any point you could just chat with the head of the company without any problem.
The same company that was wonderful to work for at 40 people imploded at 150.
I think people misinterpret the concept of Dunbar's number. It isn't how many people you can keep track of -- it's how large of a team you can hold together, provided you spend massive amounts of your time on team-building. From the article:
>Dunbar has argued that 150 would be the mean group size only for communities with a very high incentive to remain together. For a group of this size to remain cohesive, Dunbar speculated that as much as 42% of the group's time would have to be devoted to social grooming.
Spending 42% of your time on social grooming isn't a very efficient way to run a company, though, especially when you only work 8 of your 16 waking hours (and that's generally considered a good thing).
The same company that was wonderful to work for at 40 people imploded at 150.