SCOTTSO  Pages does a superb job of importing and exporting .DOC files. The only significant trouble I've seen is that sometimes a document that takes up a full page runs a line or two onto the next page, and occasionally an oddball character gets garbled. But by and large Apple's file converters work remarkably well.

Nisus imports and exports .DOC fairly well, though the importer for .DOC files is quite slow. Just as important, though, is the fact that Nisus' default document format is .RTF, which is a de facto standard for word processing documents. Any file you make in Nisus Writer can be sent to a Windows used without conversion, and they'll be able to open it in Word without the slightest difficulty.  
(Version 2.7.1)