I 've been having a bit of a play with the Pro Logic and DTS Neo 6 settings and was searching to see what others' preferences were. I found this thread and thought I'd add my thoughts to it.
With my Mission Elegante E83, E8C and E80 speakers I found no great difference between PLII Music and Neo 6 Music. The Neo 6 possibly sounds a little more full range and dynamic, but neither can hold a candle to stereo which also has the advantage of switching the 540R into 2 channel mode for more power and sounds in an altogether different league.
Comparing the PLII Movie and Neo 6 Cinema settings for general TV watching is more interesting. I found the PLII movie has the clearest mid-range but sounding a little rolled off in the upper and lower frequencies, whereas Neo 6 Cinema sound very thin in the mid-range and is bordering on uncomfortably trebly. Neo 6 cinema is noticeably louder on all channels, particularly the rears. PLII makes very little use of the left and right channels and for me the soundstage is too narrow and tinny.
Actually the revelation from all of this is PLII Custom on the 540R. To my ears this comines the perfect combination of the front three speakers for regular TV watching with a combination of dialogue (where PLII movie / Neo cinema is best) and music (where PLII music / Neo Music work well). I find PLII custom still makes in-phase sound such as dialogue still sound like it is centred on the screen without entirely coming from the centre speaker and being too thin, as with PLII movie / DTS Cinema, and without being too wide and unlocalised to the screen as with either music setting. Where differences in the L and R signal are present, such as with background music, it jumps out of the L and R speakers with great soundstage unlike the PLII movie and Neo cinema settings.
Presumebly PLII custom is something the CA themselves have produced? Maybe by tweaking the width of one of the existing PLII modes?