if you're considering the 168, then get the 268. The 168 is outdated in terms of carbon layup. The 268 is reportedly as stiff as the 177, but it's more recent and accepts wider tyres.
Assuming you can fit yourself on it, obviously. If you have very poor flexibility, like if you can't touch your toes, then you probably ought to buy an endurance frame.
As for long term longevity, i wouldn't ride a VB frame from 5y ago because composites tech used has come a very long way (now stiffer, lighter, better finished inside, cable integration, aero, discs, better ride qualities...). in 3y you'll probably want a new frame anyway. Even though modern carbon fibre frames are, in principle, immortal.
