The smps here is extremely advanced, designed hand in hand with the amp. Do a little more reading, you'll find the amps compare very well against ultra high dollar designs.
One thing to clarify... the NCore SMPS is not regulated. But it does use synchronous rectification, which confers it some benefits over using a linear supply. I don't know enough on this to explain, see the monster NCore thread on DIYAudio for more info.
I AM curious whether a regulated SMPS would have benefits above the stock one. I'm particularly interested in the Audio Power ones out of Italy that are being used by many of the 'Wire' amplifier builders on DIYAudio. Those supplies were supposed to be improvements over competent, but not regulated linear supplies for that amp. But I'm sufficiently satisfied with my NC400/SMPS600 monoblocks to leave the stock SMPS there.
One aside... there was a very proud announcement of a super-tweak linear supply being built for the NC400 modules in the 'whatsbestforum' back in April. Never heard more about it there, but I vaguely remember some questions by the designer/builder in the monster DIYAudio NCore thread trying to resolve some issues with that setup. Never heard more about that and I don't remember reading about others trying linear supplies.... so AFAIK, that question is still outstanding.
Greg in Mississippi