I have two Shimano dynamo hubs. When the hub is charging I can feel a faint buzz when velocity picks up such as when you are going down a hill but it is negligible and quickly forgotten. I have ridden all day with the dynamo charging USB devices and have absolutely forgotten it was charging. So, in general answer to you question, there is obviously a difference between a dynamo hub and regular hub but for all practical purposes you will not detect any difference when you are riding.