Although Ive only a few hours on type, the only cruise performance difference with gear down is an understandibly lower airspeed.
Apart from a higher ASI - I dont think I would be able to tell weather the gear was up or down in terms of unusual attitudes or traits noticed so far, although having only ever flown fixed u/c in the past - I find the speed can get away on you if your not on the ball - particuarly when setting a slightly lower attitude for decent without bringing much power back.