You tube is taking me back to my very early super 8 days with the films they have uploaded. I watched Kronos the very first film I hired from Derann, a b/w 4x400ft. My memory had faded about this one. After watching the full version the abridged one worked better.
I noticed it was on e ebay last year too. Another one is The Blood Beast Terror. I have the bluray, but the 4x400 works better as does Island Of Terror. Some of course don't work as well.
I think depending on the film 200ft extract worked OK for the Disney titles and some others where they didn't try to tell a story, 400ft never seemed long enough and some tried to get to much plot in. 2x400ft or 600ft were the better, then 3x400ft, but they wasted footage with credits on each reel. 4x400ft at the time when a lot of films had shorter running times was in the main not too bad. Then complete features I liked too,again some could have been abridged but it was proberly cheaper to print them from the negatives than start to cut them down.
I missed buying some titles because they weren't in scope, kind of regret that now. I also missed some good titles by sticking to the main dealers, although Regent Films did have a good selection of imports.