To bi or not to bi-wire Spendor S8e

Has anyone evaluated the sound of the Spendor S8e's biwired versus using the supplied jumpers? How about substituting Cardas jumpers for stock Spendor jumpers?
I know two Spendor dealers who insist that, for any given dollar expenditure, it is better to buy one good set of cables than to bi-wire. However, they both insist that putting in better jumpers is a must-do thing. These jumpers can be, themselves pretty expensive (One dealer uses short NBS cable as jumpers).
I suggest doing a blind test at a dealer to determine your answer if possible. I've experimented w/my Spendors w/the stock jumpers, biwires, etc. and have found that they all sound the same. BTW, some very knowledgable dealers demo their products with the stock jumpers in place, so at least some dealers don't consider it a must do thing.
I have noticed with my pair of S8e's, that jumping to the lower connectors sounds much better to me than jumping up. The
speakers have more coherence and detail. I'm running Analysis Plus Solo Crystal with jumpers made of the same cable.Bass has more impact with the Solo jumpers than with the stock jumpers.
I'm using the copper Cardas jumpers! I thought they were smoother sounding or it could all be in my mind but playing around with my tube traps (or speaker positionng) and Argent room lenses yield bigger differences. I can make the speakers sound a bit warmer or have it more dry. What amazes me about the 8es is, when set up properly, is how they resolve ambient information. For example, on Patricia Barbara's song "For Company" every strike of the drum/snare the sound reflections off the wall is so clear. Very rare to find a speaker that can resolve room information so effortlessly.