When only comparing Class D amps, i.e. NCORE NC400, NC1200, and ICE EDGE AS1200, the differences I hear are:
NC400: The NC400 has a bit more of an upper midrange “bite”
NC1200: Similar to NC400, a tad quieter sounding
ICE EDGE AS1200: Not as “gobsmacking” and the bass is not as well delineated
I believe for the Kickstarter price that Leo is selling the BOSC amps for and if you need that kind of power and want an amp that runs cool, the BOSC is a good deal. You just have to make sure it is compatible with your system from an electrical standpoint, ie input impedance, overall gain, and output power. This is also a “set it and forget it amplifier”...there is no power switch and you also should not turn off your preamp. Leo did this to save some costs which is understandable.