If you are using attachments in CRM to store documents that you are working on it's not very user freindly if you want to update the document in CRM. You have to:

1. Open the document from the note in CRM
2. Edit and save a copy of the document locally
3. Update the revised document by either adding the document to the existing note or attaching the document to a new note

All users that I have encountered expects to be able to edit their document and automatically updated it in CRM when they click "Save" in Word, Excel, PowerPoint, etc.
I know that the reply will be "use SharePoint" but not all Customers have SharePoint in their organization or perhaps the project is not large enough for implementing SharePoint.