Bruno, I also definitely prefer DPLII to Neo:6. Although I really didn't consider it to be an "echo" effect, it nevertheless didn't sound as realistic to me.
As to changes in the surround parameters, I think that it's more likely that you're recalling a discussion of the ones available in DPLII, which are more extensive. "Dimension" varies the amount of extracted ambience which is sent to the surrounds, and to some extent can help on recordings which have a relatively low amount of ambience mixed into the front channels. "Center Width" varies the amount of equal left/right material sent to the center speaker from none("phantom" center then exists)to the maximum amount for a strongly anchored center image. "Panorama" sends some front channel direct sound(not the ambience)to the surrounds to "widen" the front sound stage and is an effect I don't care for, although I wonder if it simulates to a degree the use of separate "width" speakers.
