i've have a nexus8 on my flatbar crosscheck commuter for 3 months now and am very pleased with it. Legot hit on all the weaknesses of the hub but one: sometimes i want a gear jump that is more gradual than the nexux provides. that's a small weakness.
All of those minor annoyances aside, i am very pleased with the the hub and will not be changing it any time soon.

One thing to think about: with the crosscheck, i get sliding dropouts, does the ibex have this option or must you use a chain tensioner?