Moving the follow up from the WiKi thread to here.
Yeah that can certainly go fast, but I’d always say they don’t go exactly as fast as they might seem on paper. Meaning a 24” — doesn’t ride as fast or as efficiently as a 36”.
But for me it’s all about a slower cadence and a new type of challenge, balance feeling and muscle workout.
I would however advise the adding in of say a Nimbus Oracle aluminium frame into the budget for this, not to mention a decent rim and spokes. While I know the hub is costly, the other costs are important for the whole package to be solid, light and reliable 
Let us know what you decide and your geared journey.
(I think you can tell I’m a tad obsessed! 
)