Does the"quality" of jumpers affect the sound?

If you don't believe that splicing a four-inch piece of inferior wire into your primary speaker cable run will effect the sound, then no, jumpers made from the same cable won't make a sonic difference. Use the brass bars. Whether using expensive jumpers make a big improvement, I can't say. I will say that inferior connections can certainly degrade the sound.

Tvad- Wiring into the upper post and jumping to the bottom is something I've been doing (and suggesting) for quite a while also from recommendations by Tannoy and Stuart Marcus (Vampire Wire). It's good to hear others using this technique.