Went by the retailer where I bought the World Sport, and they can replace the original setup with a 3 speed Dual Drive, so I'll end up with a 3x8 configuration, for €300/$400. I wish I had the skills to do this myself, but it's still cheaper than getting either a Touring, or jump ship and go for a fast Dahon/Tern.

Speaking of witch, I'm having a problem changing gears, where gearing down from 8 (1st smallest cog) to 7, or from 7 to 6 doesn't work and I have to shift down one more gear to actually change gears: Could this indexing problem be due to the Shimano RD-2300 derailleur, the Shimano Tourney shifter, the (brand new) cable between the two parts, or maybe all of the above?

If that derailleur is very cheap, I might's well upgrade... in which case what would you recommend that would be compatible with the SRAM Dual Drive?

Thank you.