Marnix,
Hi. Well for testing you would really want to make sure all tokens and fields were getting rendered as well. I would suggest either emailing it to yourself using the Interactive Email Event, or run several tests beforehand with just a limited number of users you are importing. For example, setup an import definition with the same exact events/fields/etc... but only for a few users. Then after that you can edit/use the existing import definition but simply upload a new file. This way you can test all areas of the import definition, without having to recreate a new setup or definition etc... Just check the box to use an existing import definition, and then choose to reupload a new file for the import.
-Chad