If I am standing at my hangar at bk and my iPhone says 60’ I know it is accurate.
No, all you can say is that the iphone is telling you its 60ft. The only way you can determine its accuracy is to compare against another known sources. (and no the elevations on an aerodrome/dap chart are not accurate enough either). Your hangar at BK is actually higher than the landing area, so what are you using to determine this 'accuracy'?
But I let the autopilot fly the approach. Less workload. Less errors.
Perfectly acceptable, provided you understand its limitations.
Are you suggesting that Garmin and Cessna have not thought out the +V approaches?
I am suggesting they have, but probably in the US context where WAAS is readily available. I am suggesting there is probably a full page of disclaimers for their products when they are being used in countries where WAAS is not available.
Can you tell me more about the iPhone SBAS Australian trials? Or is it a furphy ?
I sure can. There is currently an SBAS signal being transmitted across the entire country. It started in JUN 17 and will run until JUN 19. However it has been deemed not to be used for operational purposes and so the safety of life message has been set to '0'. This means that all certified hardware is ignoring the signal. The safety of life message needs to be set to '1' for you to receive the signal. All 'un-certified' hardware (ie smartphones, satnav, hand held units) can read and use the signal. At the moment this only seems to be impacting aviation applications but I am sure there are others.