One 'feature' Oracle has, that is very important to some large companies, is that they offer truly full stack support, from the hardware up to the application layer. If I buy support from some PG developers and they diagnose that the problem is actually with my RAID controller firmware or a bug in my inventory management software, will they still take responsibility for fixing it?

Edit: Another aspect is how long will it take for one of those PG core developers to show up on site? Oracle already has a team of support engineers (either first or third party) in most major cities in the world.