Mattmacman. If you really want to go down the single skin path, I would go with the Rab.
The fabric used is a known quantity! eVent.
I have a lot of Rab gear, jackets, sleeping bags, fleece all very functional and well made.
Even through Rab is British , you will find better deals in the USA. Not as well known brand in the USA.
I think Rab now owns Integral Designs in Canada, They make nice gear to.
But remember these bivy/tents are designed for cold alpine areas. Not really ideal for cold ,wet and humid areas like Australia.
Rain will even come in the door as you get in and out, you will have condensation problems
I have always wanted a eVent bivy. Even though the eVent ones are the best , there are to many reviews about condensation.
Good luck with you search for an ideal shelter. These bivy/tents do look cool!

Let us know what you get an a review