If I use this construct in my asp.net web.config file
1) How and when do changes to values in the MyAppSettings.config file take effect?
2) And in particular, are such configSource files initially cached and then re-cached after being changed, or does accessing the appsetting values in them require disk hits?
This affects a design decision in the case where the appsettings value will be frequently accessed. If they require disk hits, then maybe the appsetting values should be replicated in application memory (and refreshed as needed).