AFAIK, MPEG-2 decoding shouldn't differ between different software or hardware... except for:

Inverse DCT algorithm (see DGDecode user manual: the difference should be imperceptible to human vision)
Error (broadcast glitch) handling
Post-processing (deblocking, mosquito noise reduction)

H.264 and H.265 correct the first point by specifying the algorithm that decoders have to use, and of course deblocking is included on the compression side (unless it's turned off like most BDs) instead of being an optional step at the end.