I'd say that the main work right now is validating config changes, which will become massively simpler and more assured.

The actual migration will be trivially obvious in terms of validation (compiled content output files will remain unchanged, so you'd know that it's safer), and very scriptable.

It will, yes; we'll go from config spread around ~7 executable files to being in 1 executable file (CommonSettings) and ~1000 static files, of which as many as a dozen might be involved in a single wiki's config (but production will read from the single static 'compiled' file).

J.