I occasionally with cycle through some of the other modes on my Denon receiver. For example, 5 or 7 stereo modes so all my speakers are getting the same signal is interesting at times. Also, the Denon's "Widescreen" mode is interesting as it is similar to PLIIx in that it takes a 2channel or 5.1, and creates a 7 channel experience simulating a theater.
For movies, I doubt I'll ever replace DTS or DD modes for Stereo as you would be missing out on the surround effects, but doesn't hurt to try it. Does your receiver have "Direct" or "Pure Direct" modes? Those should sound even better than Stereo mode.