Afaik, the problem is that both nodes will have to support that. XOR will not gain any speed improvement as one can easily graps from the provided equation in the online help.
I think for a speed bump one had to choose balance-rr, but I couldn't convince OS X to support that. OS X by defalt uses XOR itself.
I have now prepared my multiple-link scenario and I will run some tests tomorrow.
Cheers,
budy