It would be really nice if the duo used the XLR-1/4" combo jack as input & output jacks.
This would make it easier for people that use mixing boards to use the duo.
I play multiple instruments so to be able to use the duo as a effects send/return for a TRS board would be great.
The MOD Duo actually has TRS output connectors. You can hook up the duo to balanced equipment via a TRS jack to XLR cable, or a simple stereo jack cable if the equipment supports it.