So far from my still limited testing on the Pixhawk 2.1 with an 800mm Electric helicopter, the vibration profile is quite low. It is mounted only by the medium black foam blocks that shipped in the kit from the factory.
Since it is a helicopter space in the horizontal plane is at a premium so side mounting as i did is an easy choice.
Once the PIDS are a bit better tuned i can provide some logs of how it may, or may not be affecting vibration dampening. I can say so far there do not seem to be any adverse effects, but after more testing i can be more conclusive about that statement.
As long as there is nothing that can physically happen to the imu dampening or the unit in general am i to assume that although it was not intended to operate in this fashion, i am safe to do so provided i keep getting desirable behavior?
It it just that no testing was done in the manner regarding side mounting, or other orientations? I do have a location i could possibly mount that would be at a 45° angle to the mainshaft above the tail boom block, so closer to a horizontal mounting than i am at currently. But once again, if the data continues to be positive, is it worth moving it?