From what I can best interpret, for those of us who windsurf or foil out into the middle of Moreton Bay, a level 50 or above PFD is mandatory if more than half a NM (900m) from land. Nothing else. Is this right?

Yes, that's how the MSQ website reads to me. just the pfd in 'partially smooth waters'.
Although I reckon a personal beacon is also a great investment /insurance for a fairly low cost, and could save everyone concerned a huge amount of search time if something went wrong out there. (Even though it's not mandatory.)

Yes a 50. Not a 50 S which is what everyone wears. A 50 is yellow, red or orange. A 50S can be any colour, (usually black.) A 50 S is legal in smooth water. Southern Morton Bay, lakes and rivers. This is for boats. I'm not sure if there is a different rule for buoyant craft like windsurfers, surf ski's etc.

Windsurfing,dinging,kite is not a vessel there is no mandatory rules we are seen as pedestrians like a surfer.

What your reading is MSQ (guidelines) regulations for vessels. Windsurfing etc is not defined as a vessel under the regulations. How ever - you choose to venture out without correct safety gear deliberately (2 NM or more) and it goes pear shaped - then you will most likely have to answer to other Governing organisations - AMSA, State Police etc. Lot of people read the laws and determine their way of interpreting them then they get bastardised easily by word of mouth around sailing groups.

We've all done it - pushed our limits - think about competitions the ran in the 80's and 90's - how would they stack up now given the measures in place for safety.

Bigsnut said..
Windsurfing,dinging,kite is not a vessel there is no mandatory rules we are seen as pedestrians like a surfer.

Do you have a source to confirm that? Under most jurisdictions, windsurfers would be considered small vessels and need to adhere to the same rules as a small sailing boat for instance. Some states make then exceptions for windsurfers and the like, for instance different requirements when staying close to shore, or no need to carry a radio but in general I doubt that we are not considered a vessel like you describe.