If you expect accounts to go from $0 to $1MM in a single deal, yes you need to send in the field sales cowboys. Your revenue will be chunky and hard to predict, and your business will grow slowly based on long sales cycles.

Dropbox will have million dollar enterprise accounts. They'll get to that size gradually, with a nice smooth revenue ramp, and without a financial model based on sales heads. The negotiation will be easy, because the customer will call them after too many people are expensing the product

Quantcast gets million dollar customers over the phone by starting with a $20k test buy. Less elegant than Dropbox, but not too shabby.

Nerds should be all over this stuff. These decisions get made in the earliest days by the founders. That's us, here. Investors love companies like Dropbox, and get a sick feeling in their stomache when they see a company based on field sales doing big deals.