The big differences in the IOSs:
2013 IOS S9: Avid Elixir hydraulic disc brakes, FSA Gossamer crankset and BB, SRAM X9 shifter and RD.
2014 IOS S9: brand X mechanical disc brakes, brand X crankset and BB, Dahon Neos shifter and RD
The difference in weight is the weight of the better components. The frame is the same, but the 2013 feels tighter overall.
The Dahon Flatpak handlebar stem is mickeymouse. The "tensioner" is a plastic shim over a weak spring, so the bars wiggle (roll, and yaw, in aviation terms). I corrrected this with two layers of duct tape on the bottom half of the h/bar clamp, with a cutout for the tensioner. The handlepost has flex.
The closer comparison in the 2014 MY is the Dahon IOS vs. the Tern Node. The Eclipse is simply in a different league. The Andros h/bar stem: rock solid. The Physis handlepost joint: rock solid. No flex. Tern obviously cares about every detail, and the ride and handling reflect that. The Andros stem and Physis joint are in the Dura-Ace/Record/Red level of engineering.... only the parts are specific to folders, and aren't cheap.
If I had no folder, I would be happy (as in ride 50 km) with any Tern, but only certain Dahons. In the past, the Dahon gems were the 2008-2011 Cadenzas, the Jetstream, and the high end Mus. The 2014 Dahon IOS S9 is not a gem, but the 2013 was. If your riding profile is more utilitarian, not high performance, you may not even notice the brand or model year difference.
Last edited by maunakea; 05-10-14 at 06:44 AM.
Reason: more pontificating