This ain't the first time we Fools have locked horns over (NASDAQ:AMZN), nor will it be the last. I'd call last year's bout a split decision, with the real winner depending on how long-term your investment style might be.

I find it interesting that my honorable opponent today stood on the opposite side of the fence last time. Has Alyce suddenly become a value hound, keen on joining the Motley Fool Inside Value team? We'll see about that in a minute. For now, I'll pick up the bullish banner she left behind in the dust.

Up, up, and away!
Amazon's stock price has jumped up like a kangaroo on a pogo stick over the last year, giving shareholders almost a 180% gain while returning to levels not seen since the turn of the millennium.

And yet the valuation picture looks much different today. Back in 2000, Amazon was unprofitable and still finding its identity, with a mere $2.8 billion in annual revenue and massively negative cash flows. Now, the company enjoys a $12 billion revenue run rate, $700 million in positive free cash flow over the trailing 12 months, and consistently solid earnings.

This leads to measurable P/E and price-to-cash-flow ratios, and a company expected to grow earnings by about 23% a year for the foreseeable future could surely be allowed to trade around 2.4 times sales, right?

So Amazon isn't exactly cheap. But sometimes you gotta pay for growth, or be left standing empty-handed as the Rule Breakers among us enjoy the benefits of a rocket ride to the stars, never to touch today's paltry prices again.

You've seen it happen to Google (NASDAQ:GOOG), which never looked cheap but keeps growing into ever-rising expectations. The same goes for Intuitive Surgical (NASDAQ:ISRG), or Apple (NASDAQ:AAPL), or Cisco Systems (NASDAQ:CSCO) -- if you just keep your eye on valuations and never take a leap of faith, you'll miss out on handsome rewards.

Connect the dots
The companies I just mentioned have a common denominator in that they are all indisputable leaders in their respective fields, and each is an impressive innovator in its own right. Amazon fits that mold. Not content to beat bookstores like Barnes & Noble (NYSE:BKS) and Borders (NYSE:BGP) at their own game, Amazon is now trying its hand in online movie delivery, fresh fruit sales, and giving small businesses easy access to its massive data-crunching and physical-warehousing capacities.

Some would call the strategy unfocused. I disagree, and call it visionary. Amazon can't succeed in every endeavor, but that's OK -- if you never take any risks, you'll never reap the rewards of being a first-mover in a field you just invented.

That tendency to embrace calculated risk makes Amazon a lot like Google. And I think they both deserve their rich valuations.

Wait! You're not done with this Duel. Go back and read the other arguments, then vote for a winner.

Amazon is a Motley Fool Stock Advisor recommendation, Intuitive Surgical is a Motley Fool Rule Breakers pick, and Borders is a Motley Fool Inside Value selection.

Fool contributor Anders Bylund owns shares in Intuitive Surgical and Google but holds no other position in any of the companies discussed here. You can check out Anders' holdings if you like, and Foolish disclosure keeps our content free from bull.