I've setup DOSBox Pure under RetroArch and set it up as a normal emulator (bypassing the built-in DOSBox stuff in LB). I'm having an issue using the pause screen to exit out of the emulator, it does not actually exit, but instead returns to the emulator but, mutes it. Attempting a second time unmutes. I can still keep a keyboard around and exit out with the ESC key, but I do like trying to do everything from a controller. Note, other RetroArch cores exit out just fine this way, but there is something specific about DOSBox Pure.
Steps to reproduce
1. Hit Xbox button on controller to bring up pause menu
2. Chose Exit Emulator.
Otherwise DOSBox Pure under BigBox is quite amazing!