Is there a way to extract Discogs styles? I can get Moods and Genres where I need them, but I was hoping to add Styles to an import field (custom or otherwise).

You've answered your question. :). Discogs Styles get saved to Mood.

There is a built in template for a custom field named Style. (Preferences-General-Custom Fields). The mappings are those used by Audirvana. You can always change the display name to Styles if you wish. You can create a simple action as follows to move Mood to Style and then clear Moods.

Copy the Mood field to the Style field
Clear the Mood field

You can run the action automatically after every Import from Discogs by configuring Preferences-Discogs-Advanced Run action after import.

Using a UDTI named 'Style' can be problematic as the name will not be consistent across all audio file types. You're much better making it a custom variable where you can display 'Style' but control the low level mappings. You can place Style on a custom editing panel so that you can view and edit it directly. If you want an example of a custom edit panel containing Style, download the Audirvana Mappings from the Resources web page's template section.