Some napkin math:

Dropbox: $1B in revenue / $10B valuation (10x)

Box: $400M in revenue / $3B valuation (7.5x)

The real question is earnings(which we don't know yet for Box) and whether Dropbox has a compelling case that it grow faster than Box to justify the higher multiple.

I estimated theri EV/R's (substract debts add cash to valuation) and I get Dropbox 9.0 - 9.5 and Box little over 6.

The real issue for me is that file storage is ultimately low profit margin business when the growth maxes out. The end game comes in next 5 - 10 years during a downturn and Amazon, Google, Microsoft, Facebook, or some Chinese company buys one or both of them out and gets the brand and the customers.

You have your definition for Enterprise Value flipped - it should be (Equity Value + Total Debt - Cash & Equivalents + Non Controlling Interest). If you are subtracting debt and adding cash, you are typically looking to get equity value from EV.

Your Box multiples look to be correct - looks like they trade at 6.1x on a trailing twelve month revenue basis, and ~5.0x on a next twelve months revenue basis.

Given that Dropbox has a $10BN valuation and a $600MM line of credit from the big banks, I would expect that their trailing revenue multiple is ~10.0x.

Box's revenue for this past fiscal year is about 600M, so more like 5x.

Right. That keeps dropbox at $5B. More if their path to profitability and more look better than box.