CMSWatch says that although Trends: Microsoft has released free migration tools for Notes/Domino, it is the custom Notes/Domino code that makes it hard to switch.
I’ve architected Notes/Domino applications as well as solutions on other document management and collaboration platforms and I’ve ported applications from one platform to another. Platform migration tools are usually good at moving apps with little or no customization. The “problem” is, Notes/Domino 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.
If you accept that you are essentially starting over for all but the simplest applications, your next problem could be with end-user expectations. A lot of the functionality vendors are just now getting around to incorporating into their offerings has been present in Notes/Domino for some time. If the goal is to port the highly-customized application with a 0% loss in end-user functionality, prepare yourself for a substantial development effort and, potentially, the acquisition and integration of best-of-breed components to keep the app as functional as it was before.
This is probably true for any platform migration project. Although you’d like to think that the end-user requirements are de-coupled from the underlying technology choice, platform-specific features or strengths always seem to find their way from the platform feature spec sheet to the list of features end-users can’t live without. Sometimes, that’s because the platform might have been originally selected because of those strengths (i.e., platform X has strong collaborative features or platform Y has great Office integration, for example). Other times, it is because developers are inherently lazy–features that rely on functionality that comes “for free” or is built-in to the platform are often at the top of the priority list.
I think platform migration utilities are most efficiently used as a marketing tool rather than a technical tool–they give the sales folks an answer to the “what about our existing applications on platform X?” objection. Use them to migrate your simple stuff, then start the real work of planning the migration of your customized apps.