Are you allowing your capture hardware/software to IVTC or are you using a decomb/GreedyHMA plugin? I think you said you were using Avisynth so probably the plugin filters.
I'm just trying to get my mind around how you deal with the 2/5ths of the frames that only exist as interlaced, since deinterlacing them is damn hard to do well. You would have to reconstruct them correctly somehow without introducing artifacts.
Again, maybe I don't know what I'm talking about but all I have to go on is other video guides.
I'm starting to be remarkable impressed with what you guys have done. (More than before.)