I've seen in RTC 4.0.6 that the multi select checkbox presentation is marked as deprecate in the editor configuration in the 4.0.6 client and that a warning is shown on every instance of the presentation in work items displayed using the browser rather than the client. In the RTC 4.0.6 new and noteworthy "This warning is in preparation for removing the presentations entirely in a future release. Work items that use these deprecated presentations must be reconfigured to use supported presentations."

From my testing, it doesn't seem possible to "reconfigure" the existing attribute's presentation to an alternative multi-select presentation (only valuesetcombo and valuesetpicker kinds are available).  Also I've previously experienced difficulty with the restriction that an attribute's type cannot be altered once there is a work item has been created with that customisation. So my only option seems to be to create new attributes with different types (either Enumeration List or String List) to exploit the new presentation kinds that support multi-select.

• Enumeration List type based on the existing enumeration, would allow me to select a Checkbox presentation, but still does not enforce the dependencies of a valueset when using a multi-select presentation.
• String List type will allow me to restrict the values based on attribute dependencies with with a HTTP Filtered value set, but I can't use a checkbox display, only a "picker" box and I can't restrict the values to the value set returned because of 240267

So not only creating new attributes with diffierent types would be hugely inconvenient - requiring manual migration of the data over to the new attributes plus changing all reporting, queries, scripting etc that use the existing attributes - but the options don't resolve all the issues with multi-select presentations anyway!

What is the RTC recommended migration strategy for this deprecation issue?