Speaking purely from a mechanical/speed/efficiency viewpoint, the 2% difference isn't that meaningful. But there's a hitch in that most (all?) IGH hubs are lose efficiency with load, so they'll be least efficient in hill climbing, when you need the most help. Some are also less or even least efficient in the lower gears compounding the problem.
But for general cruising around, you'd be very hard pressed to find a difference.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.