Efneo 3 Speed Front Gearbox

Gearing is too tall for an MTB with a smallest (effective) ring size of 28T (and you'd never need the largest effective size), it looks a nice solution for some uses though and a mate has bought a setup as an early adopter for a high power hub motored E-bike.

The trouble with hub geared rears is the gear spacing is setup for use with a single chainring, to work effectively with the efneo it would need closer ratios, you'd only really be able to use 2 of the 3 front gears with an Alfine hub.

Best uses (to my mind) are either on a single speed (to give you 3 gears thus making it a bit more useable) or a dedicated commuter using something like an older 8 or 9 speed road cassette to give nice tight ratios and you can use the stationary shift facility to select a smaller ring at stops for the launch.