I'd agree with Nick. 8TC gets all the coverage, but I don't hear much difference between 4TC and 8TC. If a speaker is made for bi-wiring, it will usually sound better bi-wired. This kind of thing is system dependent, but imho you're not giving up much with 4TC versus 8TC and the benefits of bi-wiring would outweigh any advantage of 8TC, even with jumpers made of 8TC. If it were me, I'd bi-wire with 4TC.
