As far as I know it's unbalanced outputs... a TRS to XLR adaptor wont do anything for you.
I have a GT-1B and have tried the new GX-1B a few times. It's definitely mechanically better built, and the preamps have been renamed to contemporary offerings (or hints at more contemporary offerings) but I would not say it is sonically superior to the GT-1b.
You might find the screen/UI a little bit easier to work with, though.
If you want to go deeper into the Boss AIRD/Modelling environment, save your money and step up to one of the GT-1000 units, instead. The 1000Core is quite a step up in features, routing, and I feel that it sounds better.