wbt nextgen spade, rig or sound idea

You'll probably compromise the resale value of the cables/spades.

It would certainly work, but it would be less of a connection. When the crimp sleeve is properly installed it creates what is referred to as a cold weld. This basically creates a molecular bond between the conductor and the crimp sleeve. Once you tighten the Torx screws they are essentially making contact directly to the cables conductor due to the cold weld. There is no cold weld with the current bananas being inserted into the spade body. Now, will you hear a difference? Possibly, but not likely.