When I had someone build me NCore amps, I asked numerous people that same question. Answer came back consistently that there was no loss of sound quality. Even the designer has stated this, I believe. For that reason, I opted for a single chassis (small footprint) stereo NCore implementation with one SMPS. Now, I have not done a side-by-side comparison, so I can't confirm if there is any sonice difference, but I have been very pleased with the one SMPS amp I am using. I don't think you can go wrong either way. If you know you don't need tons of power, why not save space/chassis/cost? I am pretty certain that the NCores will not be a weak link in your system by a long shot.
Best, -dB (a unit measure of noise)