Found this while searching for price on Curl D9, this relates to the Curl i4, internal gear hub:
A potential downside to the Curl is the relatively modest 187 lbs (85 kg) maximum load capacity. That’s only 77% of the Brompton’s capacity, but it still suits many riders. And it’s a nicely made bike, as you’d expect from Dahon.
That load is well below other Dahons, usually 231 lbs max (and higher with Deltech). I am guessing that is because of the hub bearings of the IGH, versus a derailleur hub. This is one of the reasons I have cited for (my perceived) market failure of the Dahon Speed TR (touring), with IGH.