[chromvis]

I tested Ublox neo M8N GPS with external mag on two copters (one with Sparkey 2 and another with Revolution)
GPS purchased from https://www.amazon.com/gp/product/B01DEJRSB2/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
I was using LP "next" release r1212 with autotune. Autotune on both systems went very well. In complementary mode both copters have solid feel, very responsive.
After changing to INS13 mode I did full calibration outside with good fix and far from interference. System Health is all green but copter fly sideways. In velocityRoam it jerk away (the one with Sparkey 2). The one with revo I did not even dare to fly - PFD rotate horizon all over while SystemHealth is all green.
Vibration from SystemIndent Noise (as described by Cliff) is around 10 which is 10 times lover than acceptable level.
I read, that M8N is less reliable than M7N, I will test it with M7N, but has the EKF analysis and overall GPS software  been tested for reliability?
It does not seem possible to use it now at all without risk to major crash and even injury.

[TheOtherCliff]

If mag health is green, but PFD is moving wildly all over the place, you probably forgot to set the aux mag orientation.
https://librepilot.atlassian.net/wiki/display/LPDOC/Aux+Mag+Setup+and+Calibration