You guys --- coriolis effect?
It takes time for the gyro to warm up because it uses electronic and piezo components, my start up is always the same. Set your tail trim before take-off(in HH tail blades don't move and stays centered), run it up for 30 seconds then shut it down, turn power off then back on and retrim tail and your gyro will be rock solid for all your flights. In cold weather it gets worse you should let your bird sit outside for 5 minutes minimum to stabilize the temperature, then run it at least 1 minute to warm up the gyro before you land, turn power off/on and retrim. If you don't do this the gyro will continue to drift for some odd reason before you turn off to switch packs which is really annoying.
As far as vibration goes I have never had a issue with it, it has always been the gyro gain being set too high leading to drift and tail wag.
Hope this helps and good flying