I have had a wee play about with this, and as far as I can tell the filter function only effects the track that you have downloaded into mapsource,not what the GPS does.
when you select track properties-filter there set at Auto about the mid position on the slider, this means the track as displayed in mapsource will follow you route pretty closely.
However if you change the filter to say time-300 sec's you notice the track still follows you route but not as closely as can be seen if you look at a series of corners on the route before the track followed the corners not it seems to take a more direct line so cutting some corners out.
now I don't have a 2610 but a 60CSx and briefly used a Quest1 there is a menu setting that allows you to change the track recording method by distance/time or Auto, on the 60CSx it's menu-track-setup on the quest it was something similar (but less options over the record method) so I can only assume the 2610 has something similar
I just dont know.No amount of changing the filter settings does anything to alter the dowloaded track
.Try it on what I have posted here nothing happens.