Well apart from the two GoBikes I brought in from Belgium I've never seen another one, spares & accessories have been promised along with the promise of all being revealed on the re-vamped website. That was last year. Spoke to Philip Brook, the designer both on here and by e-mail regarding my mis-givings about the GoBike's handling.
I have found that compared to the Birdy the GoBike is very trick looking but nowhere near as good in the handling department, Philip says mine must be wrongly set up, But I am sure that an elastomer type damper is need to stop the front sprung fork from going into a bouncy spasm on some bumpy bends. Add to this the very strange rear swingarm configuration (which, IMHO means that even without a rack, luggage tends sway about on bumpy bends, thus I find it hard to trackle a bumpy bend with the confidence that I always had with the Birdy (I haven't tried the newest Birdies as yet)
I gave my Brompton to Nia, my Daughter, as I found it too short (and I'm not tall) and not comfortable (I love the super small fold but feel the design, brakes etc need a good kick up the elastomer.
I would have another Birdy but the IF Reach or IF Mode would be more desirable when they arrive in the West.
Good luck with your choices.
Chop!