Single output at amp, tri wire at speaker. Any benefit?

No, its not the same. Bi-wire and try-wire are awful ideas if you're talking about buying three sets. If you already have 3 sets though, different story. Try and see. Be aware you may well find they are not the same, one is better than another depending on where its used, and the only way to know for sure it try and see. 

If speaker manufacturers didn't think it made a difference, they wouldn't bother providing separate inputs.
As millercarbon mentions, if you have the cable availabe, just try it out.

If you don't most cable companies will be able to make a cable that has one set of leads for the amp and 3 pairs of leads to go to each of the terminals.
Even if you still use jumpers, you will notice a difference when using different cables.
Bob

First try running the main cables to different terminals on the back of the speaker, with the jumpers adjusted accordingly.  You may find a difference with using the tweeter vs midrange vs woofer input as the one that directly receives the signal from your amp.

Thank you . Haha! The solutions proposed are so logical. Silly of me to not have tried those out first. 
I will do the binding post jump first. 

Cheers
Jag