After spending a week trying to make a good flightcomputer I just decided to make a wrapper for the old one, to be replaced later. The UI for attitude control is hooked up and has some basic functionality although some bits are still missing;
Connections are now cached on VesselSatellites with event listeners, will probably implement in ISatellite and remove ConnectionUpdated. Have to adjust NetworkRenderer to show path for active vessel only.

If you want to volunteer by writing a new drive routine for the flight computer, go right ahead.