This dovetails nicely with the new named-format feature: I'd love to be able to reference named format strings inside other format strings. I have several chunks of format code that get referenced multiple times when naming a single file, and it'd be handy to be able to pull those out and manage them in a single place. Similarly I do a lot of things differently for various-artist compilations, and since I store everything as a lossless image + m4a tracks it'd be handy to be able to have rules for "if this is a FLAC, use this named formatting string, otherwise use that one" . . . without having to cram it all into one crazy-long block of code.
Either way just getting to explicitly name the format strings is a huge help, so thanks for that.