Is it possible to plug in only 1 10GE interface into a two port (6708) or four port (6716) block to get the full 10GE bandwidth?
Not sure where you got the 6716 module, but here is some information regarding the 6708 module:
Q. Is the 8-port 10 Gigabit Ethernet module not oversubscribed if I only use half the ports?
A. Yes, you can use only ports 1, 2, 5, and 6 to provide 40 Gbps local switching. To make it easier for you to configure your network, we have a new software command for you to go into performance mode. The software command
router(config)#[no] hw-module slot x oversubscription
will administratively disable the oversubscribed ports (ports 3, 4, 7, and 8) and put them in "shutdown" state. In this mode, the user cannot do "no shut" on the disabled ports. When user do "show interface" on the disabled ports, the output will show "disabled for performance" to distinguish between normal port shutdown and shutdown for performance.