If an app is not dropbox compatible, it usually has some ability to open the file in another program which will be. I simply have not had an issue with any office productivity products in terms of struggling to get the data out. Oh, there are different methods, and certainly some apps are better, but I'd argue that a college student could survive with the iPad and a keyboard -- not saying it is ideal - as it isn't - but it could work fine. Assuming they had a iPad-compatible wireless printer, of course.
But personally I reserve all substantive writing - outside of the context of notes at a meeting - for my Mac. I do view power points and occasionally excel files, but I do the actual work on the Air. And even then, I rarely if ever write anything in Word anymore, preferring the simplicity of Nisus Writer Pro, the RTF tools in DevonThink, or occasionally, Scrivener.
BUT Neutron -- if she can wait a few weeks - I would try to hold off and see what the new MBPs are going to offer. All evidence points to Air-like machines, but with more power. And who knows, maybe even a retina display (time will tell on that one, but I am not counting on it quite yet). Hold off and see.