Some of you may be familiar with the Eagletree Vector autopilot (no longer available). This autopilot was probably not as advanced as Pixhawk autopilots, but in some ways it was a whole lot better. It had some very endearing qualities: 1. It had a pdf manual that a user could download, print, and take to the field with him; and 2. It had an onboard video diagnostic system in plain English that could output via a standard three line servo connector to any FPV video screen. Thus a pilot could sort out system issues right at the field, without the need to lug around a computer with an internet connection or try to remember or decipher unintelligible beeps and LED blinks from the autopilot on what might be going on in the system. I believe that the latest Pixhawks have the power to accomplish the same feat. I just wish that someone would put together that functionality and make life a whole easier for Pixhawk users.
You can find the cube user manual here:
For the diagnostics, I believe any controller with built-in telemetry and GCS could show you the system status.