it is. if you understand which hidden stats a ship have, you can use that ship in a certain track instead of another, for example van uber has hidden pitch stats as rf said, also much more grip than other ships, so it's better to use it on low barrel rolls tracks etc.
imho, it's up to the gamer to find them out using the ship till the death, it's like an experience achievement. :D
uhm, i see hd ships more bouncy, but maybe it's just my feel.
i think it changes from ship to ship...i see icaras HD way more bouncy than icaras fury, can't remember other ships tho, but iirc also agsys hd is more bouncy than fury.
but still, it's just a personal feeling :P