For many years I have been bi-wiring without jumpers. A few years ago, in an email exchange with Paul, he recommended adding the jumpers. I recall being skeptical and did not try it (though I had no knowledge or facts as to why it wouldn't work).
For some reason, I decided to try this. Last night I made a set of jumpers out of some 12 GA OCC wire and gold/copper bananas. This morning I added the jumpers.
I prefer bi-wiring with the jumpers.