So you're getting Adobe-Camera-Raw Defaults rather than User-Camera-Raw-Defaults in your DNGs as their initial settings which Bridge knows and shows a settings-aren't-default-anymore badge and you have to reset them in Bridge (or maybe ACR), and you're seeing a new Settings choice in the DNG Converter.
I am not seeing "a panel-specific toggle between the settings and the default settings" in the DNG Converter 8.6.0.254 which is what is currently on Adobe's site for the PC. I just downloaded and installed it just to make sure I had the current version not the release candidate. I don't have a way to check what the Mac version is or looks like. Here are screenshots of what my DNG Converter 8.6 looks like on Windows 8.1:
Are you still running the beta version? Are you on a Mac? What DNG Preferences are you using? Are you running the current versions of Bridge, Photoshop, ACR (PS-CC-2014.1 and ACR 8.6) or are you converting to DNG because you have an outdated version of something?