I have yet to finish a car with D301. In my testing I had several cars where it finished down very well, but some also left noticeable marring. Since most my customers want Opti-Coat or a dedicated sealant, I always finish with M205 or 106fa.
I'd agree with Greg that it's more likely the MF pad than the product. Some paints just don't seem to work well with it, which is fine for the cutting step really.
As Greg mentioned, M105 worked very well with these pads too, and they seem to dust less than foam and working time also seems longer.
Cheers,
Rasky