^^ I'm using Blender and exporting my models with a .dea extension. It works pretty well with NoLimits.
^ I don't mind adding the sounds to the Ferris wheel but I think it may be not realistic. Those Ferris wheels in the video's are smaller and the cabin's are closer to the motor. I think that's what causing most of the noise. If I'm hearing it right on the Youtube video's the sound at the top of the wheel is just a bit of wind (which you'll already hear in the simulator).
It should be easy to add a config file which contains an option for adding sound in the cabins or keeping them quiet. Maybe this is a good solution?