A few legacy (and awful) apps part of an AppStack require modify rights in their install location (%programfiles%) so that the app can write config files there. Apps run fine w/ modify rights within the AppStack, but obviously any config changes made are lost at log off.
What are my options here using App Volumes? I don't fully understand use cases for writable volumes, so not sure if that's the solution.
Just looking at VMware solutions you have 2 options, a writable volume and UEM.
Writable volume's use case is mostly when you want to provide users with their "own" desktop while still using pooled machines. A writable volume is a catch all bin which means that if a user installs an application it will be saved into his writable volume (assuming he has admin privilges). The biggest win you would gain here is that it will catch all and everything you install and even your profile will be saved (if you use the UIA + profile writable). The biggest downside to using writables volumes is that it is a ctach all bin. This means it will also catch the rubbish you user or Windows might produce.
In UEM you could select this folder the file is being changed in (not 100% sure if UEM can also catch machine properties instead of user properties but I thought it could) and create an application object for it that is related to this application. If a user would then change the file UEM would see that change, catch it and save it to the network.
The biggest difference between the 2 is that with UEM you would need to set the application to catch the file but it then only catches this. In writable volume it is just create it and your good to go. Downside is it will catch anything and everything.