Sounds like a number of improvements to RISC OS are going to appear with the A9. The improvements to the core operating system sound good and can only help to improve the end users experience.
A lot of "duplicated effort" has occurred but at the end of the day both Castle and Advantage Six have to provide a point of difference to ensure they win sales. They are in competition with each other and need to sell machines to stay afloat. It is hardly surprising that things happen the way they do.
USB serial ports will be quite useful to many people. The A9 as an upgrade to RiscStation based EPOS systems would be a possibility with the addition of serial ports.