The BMW guys mentioned valve body rebuilds in one of your links. Back when we were troubleshooting an issue with the 5HP24 trans I found some helpful literature from Sonnax. Anyway I checked their site out for the 6HPxx and noticed critical wear items that are related to various regulator valves which fall into some of your symptoms. I haven’t review any of the Audi literature so it may be a repeat, but hope it helps in some way:
Valve Body & Mechatronic
http://www.sonnax.com/pdfs/12-Valve-Body-and-Mechatronic-Service-ZF6HP19-26-Aisin-AW-TR-60SN-09D
Solenoid
http://www.sonnax.com/articles/233-Flow-Control-How-Solenoid-Design-Influences-Clutch-Circuits
Direct pdf link (Vavle Body & Mechatronic):
http://s3.amazonaws.com/sonnax-dev/uploads/pdf/pdf/12/2011_Presentation_AutoChoice.pdf