Ah. Well, you could give it a try just five seconds worth of capture and maybe see, eh? Just cap a shot snippet 5 times ever, trim the cap avi's so they all have the same start frame, use VDub to read in the AVS averaging of the five, and output from VDub. Sometimes a view compare at 200% is pretty striking, sometimes not. Depends on a bunch of stuff of course...
If you're interested I'll give you a template avs script, but I'll reiterate that for a feature film it would likely be a lot of work (not to mention time and hard drive space) so maybe even your experimenting with this would just be wasting your time. :shrug: For short stuff though, it's usually the way to go if you're aiming for max. quality given just a PC with capping abilities and an analogue home video player.

So there's all that :)

Edit: Just saw your post, and I agree about de-noise filters. I really don't like them for my chain. The only thing I actually every used AVS for (in regards to captures) is decomb/telecide and averaging. Averaging is my de-noising for captures; avoids GIGO. :)