I've been reading these forums the past few days and I just had to sign up. What you guys are doing is just fantastic.
Forgive me if this has already been mentioned, but have you guys heard of Red Giant's Instant HD software? It uprezzes SD footage to HD resolution with very high quality. Now even if you guys aren't interested in having HD versions yet, I think up rezzing with the software and then down sampling to SD would result in superior image quality.
http://redgiantsoftware.com/instanthd.html
Just wanted to throw in something that I thought might be of help.
Cheers,
Megacles