There's no such thing as a perfect team. Growing businesses are changing all the time. The complexities, the things you need to emphasize keep evolving. Do you need to emphasize supporting your customers? Or acquiring your customers? Do you need to emphasize building a second or third product which is very different than building a first product? So in a fast-growing company, the requirements on a team are always changing.
What I've learned in my career is the simple fact that even if you working with A+ players, a company can grow faster, and complexity can grow and change more quickly, than some people can actually develop skills or change their behavioral patterns or learn what they need to learn. A perfect team is a constant process of evaluation, re-evaluation, a big dose of loyalty for the folks that got you this far and then a big dose of realizing that even if you’re loyal and even if you want to stand beside somebody, they may be perfect for last year but not right for this year. If I were to rewrite the history of Marketo, that notion of understanding how and when you need to change the team, to reassemble the team for what's needed on the ground while not needlessly churning people, was the hardest thing of my entrepreneurial experience. It was also the most important because in the end, the team is all that matters.