KVCD: Temporal Smoother?

[Daagar]

I notice that most people here use AviSynth to do their processing, and tend to turn on Temporal Smoothing at either (1,2) or (2,2) levels. How much of a difference does this make?
Currently, I've just been playing around with converting files directly in TMPGEnc (without AviSynth) after having demuxed the audio from the file (if the source was divx, for example). It sounds like playing around with AviSynth might be worthwhile, especially if it is worth using this Temporal Smoothing.