well, actually, dahon frames have a very short head tube. R20 requires a 9" steerer, which has limited options. Might be nice to be able to use forks readily available on the market.
Agree with that.
On my current R20 project I'm using a solid BMX fork with V brake bosses with the R20 steerer brazed into it... MADNESS?
Yes, but it's the cheapest option for me and I couldn't find a fork with a long enough steerer.