Assuming you're speaking of .mp4 format as opposed to .avc or .m2ts, I guess its worth mentioning that MainConcept appears to produce better results than Sony AVC at a given bitrate. HandBrake (x264) is better than both.
Do you mean in some cases Lou? I've used Progressive m2ts for BD before. The 'field' box is greyed out, so can't see how I'd change to progressive. I did some experiments with MC & Sony AVC (interlaced) and they looked identical.