You must not actually do much work because all of the alternatives you listed don't work with more complex office documents. I like iWork's interface, but to call it MS Office replacement is a bit far fetched.
Everyone's needs are different, of course, but I deal with spreadsheets of thousands of rows and dozens of columns, some with VBA, lots of formatting. It works with the alternatives. Maybe what you are doing doesn't, but my stuff works.
As for Word, thousand-page docs, headers, templates, the works.