Why would you dynamically modify the configuration of your services? Why would you use a configuration property then when you plan to change it anyway?
why not? One may want to write a nice UI to switch between the classic UI and the touch UI - or to configure the smtp service. While the system/console is nice I don't think it's a good UI to manage common administration tasks.
What would be use case for this ? Why not to store that information in node itself and not in configuration ?
My personal opinion is, that the administrator should be capable to configure the CQ5 instance via the Felix Console. I don't think, that editors should be able to change service configuration (like the mail server config).
Editors might change configuration for their parts of the content. Then you save that kind of "configuration" in that piece of content, but not as configuration of services.
I am not saying the editors should be able to change it - I am only
saying an easier UI for admins would be a good example why to change
OSGi configurations programmatically
In that case: Use the JCR API. Then a proper reload of the affected services will be triggered.