A limited palette of colours can indeed look great, as ThirdEyeNuke's work proves.
The pink/red spot colour looks like it's simply a red-ish wash over white base coat - not a problem.
The white is much harder, as it's always a difficult colour to shade (while still looking white instead of grey) or highlight (coz there ain't no lighter shade of white

). Definitely worth some experiments on gaunts, using multiple dilute black washes over white, then adding further white highlights if necessary.
The gloss on the black is a great 'cheat', bringing out surface texture for little effort. But some of those gradations between solid white and solid black look airbrushed to me.