I think you need to pick the films with really great visuals to take advantage of SuperBit. On Fifth Element, for example, the picture is stuningly clear with incredible depth... when they look down into traffic, you can see uncountable layers of cars criss-crossing and when the gene-splicer is putting Leeloo together, the robot arms are flashing at incredible speed, but they never go out of focus.
A Knight's Tale, on the other hand, the picture is very sharp, but other than scenery, you don't gain much from the additional clarity. A picture heavily dependant on scenery (Cliffhanger, for example) would probably be more rewarding.
I personally prefer the SuperBit versions and buy them whenever I can, but you do have pick those that benefit the most. It's like on broadcast TV, where Everybody Loves Ray was the first primte-time show put on HDTV... Some things really don't look better when they are super-sharp...