Re seats and sales, one should not ignore the annual maintenance fees that go along with seat sales, and which continue to accrue. The maintenance contracts for three to four seats is equal in annual revenue to one new seat license. By the time wave sells 500 million seats in a year it would be collecting hundreds of millions per year in maintenance fees. My point is that to get to a more realistic $1 billion in market cap Wave would not have to sell 5 million seats that year (using your 4/1 ratio), assuming it had sold sufficient seats in prior years to meet the annual revenue requirement to support that value.
I'm very eager to see Wave's customer retention numbers as time goes on, as a recurring revenue stream from customers is an important part of Wave's business plan.
Cheers,
Dory