A good summary, but
Back to the topic: In my opinion, DIY approaches aren't the real solution, ATC in many places around Europe would file a report if you got in under very marginal weather. To add, it would be very suspicious if a single-engine GA aircraft made it to the runway (by flying a DIY GPS approach), when an airliner/business jet flying the same approach you tell ATC you'll be flying couldn't.
However, this would not happen because DIY approaches get used only in places where there is no IAP published at all. I agree that in Germany, one needs to be very careful because some pilot(s) have been done for apparent IMC flight under VFR, near an airport.
Anywhere where an airliner will be going is going to be a proper IAP.
The main disadvantages of DIY GPS approaches (when there is adequate obstacle clearance) are:
- it increases your workload (especially if you have to put in a lot of waypoints for the approach)
True, but normally you don't need many waypoints. You don't need any more waypoints than for any standard GPS approach i.e. the T-shape.
- it's far, far from legal
That depends on where, etc.
- you don't have the luxury of published GPS approaches, such as LPV, etc.
LPV doesn't exist yet. I gather there are some trials going on. LPV will be great when it comes, for those who have the latest equipment, but the flight manual supplement is an EASA Major Mod the cost of which (4 figures) will drastically retard its adoption by GA. Also, in the UK, GPS approaches will remain largely irrelevant all the time the CAA requires ATC as mandatory for any IAP.