I was obsessing all day over a slightly different issue, leaving the broadcast noise alone or accepting blocky artifacts from the FFT3D denoiser
Just a quick aside, as don't want to derail the thread, have you thought about combining the your multiple captures to reduce noise/improve picture quality? It's the technique Citizen used to create his very clean Star Wars laserdisc trasfers.
Some info from the doom9 forum: Look for the section '7.2.12 Using multiple captures to reduce noise'
There's also the Average and TooT plugins that can be used to get the best out of multple captures