If you are lucky to have a trustworthy dealer, you will be fine. My own Dahon had problems with it's front hub and my dealer removed the axle, cones, bolts,and whatever else within the hub to strengthen it and fix the problem. No problem since I bought it 2+ years ago. That it why it mostly pays to purchase the bike through a bike shop rather than an internet one if you are not too comfortable about doing your own repairs.
Hi, I have 2 Dahon D7's and the rims on both bikes were not smooth at the joint. I sanded the rims at the joint until they were smooth. Brakes work fine now, without any thumps. They are Weimann rims which use to be a good brand. The D7's are good bike for the money, just need a little work.