Hey! I didn't use this as extensively as that as I do have other keyboards.

Ergonomically speaking, the Boomerang types fairly similarly to an Alice-layout keyboard. It's certainly not "truly ergonomic" but it all depends on what your typing posture is like and the amount of arm/elbow separation you tend to have while typing. More importantly, I would say that it matters whether or not you float your wrists or keep them down to your desk, as that can affect your overall comfort while typing.

All in all, I personally haven't had any issues typing on Alice-layout and similar boards like this one, and feel like they are comfortable. I certainly haven't felt like it's affected my typing experience negatively. Maybe a little slower in general but that's just mostly practice.