Having owned two DualDrive equipped Dahons- and Chutney the Speed Pro TT in particular is most definitely Not Slow, I'm not sure that the hub was the problem-though if you've got a regular derailleur setup on there, the bike's lost a kilo in weight, which will of course help a lot. Drag in 1:1 is practically non-existent and there's not much in high/low mode (YMMV). Possible it was faulty or just needed careful tweaking. I'd agree with mzio that tyre choice is crucial, I found 28mm on the TT too harsh- though fast- and like the Jetstream XP I previously had, went to 40mm (Marathons on the XP, Marathon Racer on the TT). Done up to 140 miles on the TT…
Would recommend staying on the saddle -if out then the long handlepost is not going to like the extra stress at all, and it certainly doesn't help stability.