Hi Marc,
Some sort of monopod should always be in your kit. You need to look as a few points, like its strength, weight, construction material, and its size when extended.
If it's too short for you use while you're standing, then there may be some issues. And while carbon fibre may be very light, ir might not be able to withstand the taxi-door test.
As you've noted, there are many points of view as to whether you should use VR with a monopod, and my best advice is for you to just start shooting some images - comparitive (VR-on, then VR-off) - and see what you think works best for you.
As to brand and type ... we have two here, an aluminium Manfrotto 276B, and a carbon fibre Feisol. Both are excellent products, and both have served us well over a number of years.
The Mannie certainly passes the taxi door test; not sure that any CF pod would.
And for hiking, either can also be brought into service as a hiking cane/walking stick.
I'm not familiar with the 680, but I would happily recommend either of the above units for your consideration.
g.
Gary Stark
Nikon, Canon, Bronica .... stuff
The people who want English to be the official language of the United States are uncomfortable with their leaders being fluent in it - US Pres. Bartlet