Tiger_Moth,
The simple answer to your question is that no-one is yet sure when it'll be introduced. As to the advantages and disadvantages and other details, there have been articles and discussion on the NPPL in all the flying magazines such as Flyer and Pilot recently. If you're not reading these yet, you should be, if you're serious about flying. There's a lot more to being a pilot than learning how to manipulate the controls.
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Whirly
To fly is human, to hover, divine.