Coudray knows his 4cp. His platform is netseps.com if you want to try it out
I've used netseps before, and had good results, although with sim process separations.
I'm a little naive to four color process printing, I've never understood the "seps" as I've had the best results by just lightening the image a bunch, saturating it more, and sticking it in illustrator and printing the CMYK at all the same angle and dpi.
In something like UltraSeps a CMYK image cuts out parts of the colors from under the black and other areas, but I've always had better results just using a RGB image, having inks straight from the factory, setting expectations with the customers, and crossing my fingers it looks good