I did a similar calculation... they are spending about $40M/quarter on sales people who are generating an incremental $5M in recurring revenue each quarter. Not great, but not a disaster. Especially when you account for the fact most of the sales people are new.
A year from now, with the publicity from the IPO, and more experience and natural snowballing, the same $40M salesforce could be generating $15M in incremental revenue per quarter. That would be a recipe for a quite valuable company.
He came to pretty much the same conclusion that I did:
"When you look big picture, I believe they see themselves in a winner-take-all battle vs. DropBox and in this case, the strategy — while amazingly cash consumptive — does make sense."
5 years from now, I do see a possibility that Box is doing very well in enterprise, and Dropbox gets squeezed hard in the fiercely competitive consumer/SMB space.