The *problem* is, Notes/Domino [and I would extend this to any real CMS platform] is often used to develop complex, highly-customized applications. For those, there's probably no getting around a complete re-development effort if they are to be moved at all.
The best one can hope to do is migrate the content and success will depend on the quality of the content. If the content is well structured, it is often possible to use automated migration logic to map fields from one repository to another. If the content is just free text, the best you can do with automation is to push the content into an equally unstructured system. Of course, then your pristine new system will be as cluttered as your original system - probably more-so since much of the organization that was implied through navigation will be lost.
Not to scare you, but if you are switching platforms, be prepared for the cost of migrating your data, as well as training and loss of productivity. James Robertson of Step Two sets some realistic expectations in his article Spending Patterns During CMS Implementation. On the bright side, this work often forces critical business decisions and activities that directly improve the way content is managed within an organization. For example, deciding how long to keep around content, eliminating redundant or outdated content, organizing content more effectively, establishing ownership and processes for content.... If you want to be successful in this initiative, you would do this work anyway. Otherwise many of the problems that hampered the original system would be ported to the new system where they would be equally problematic.