I went from a flat bar hybrid to a aggressive carbon road bike with drops. The handling at first felt skittish and much quicker than the flat bar hybrid. I have had the chance to ride and familiarize myself with a couple other drop bar road bikes before getting my own, and that quick steering, skittish feeling compared to the hybrid was there on all of them. IMO, most of it is due to the much narrower hand position on drop bars. The closer your grip is on the handle bars, the more skittish it will feel. If you were to chop your hybrid's flat bars so that the grips would be as far apart as those of your Jamis' I'd bet it would feel a lot more skittish.