Back to the OP, when I load my bike down it definitely feels different, but not in the area of speed and acceleration - it handles differently. It loses it's "crispness" I guess you'd call it, but it seems more stable. (I'm not saying it is more stable, I'm saying it feels more stable). Also it's a little more comfortable loaded. I don't know why, but I suspect the extra weight is compressing the tyres a bit for a softer ride (just a theory). But average road speed (about 14 to 15 mph) is not different, and acceleration from a stop doesn't seem any different. After all, slow is slow! lol