I'd love to know how the Alfine idea came up, and what alternatives were also considered. The easy way to give a Brompton lower gears is to fit a double chainring (or just a smaller one!).
Not sure, As someone who rides a Brompton with an 8 speed hub, and twin chain rings (manual shift on the front). I'm not sure it's as good an idea as an Alfine 11 would be. I think it's not just about being low on the gears, but the range of gears. I did the maths of what he was running, and his smallest gear is about 2.2m, which isn't that big.
The big problems with the Brompton for this type of ride are the tyres, and the suspension block. The options for tyres on the Brompton are limited, Roger was running Marathon Greenguards as the other option of Kojaks just don't have the puncture resistance needed for a ride like this.
The suspension block, Roger had a prototype unit, but I don't think it's enough to deal with the amount of losses in suspension.
J