Many thanks Michael and Carsten for your advice. To boil it down, I guess the overall answer is ‘no’ I cannot capture at 25p without additional hardware – either the Blackmagic or Kona card (according to the article), or Panasonic frame convertor. (So more money for more kit needed!)
As far as the 900 not doing variable speeds – I realise it doesn’t have the flexibility of the varicam but If I simply wish to get a good slomo, I assume I can easily shoot 50fps or possibly 60fps and convert to 25 using FCP frame convertor?
Overall I agree – some test shoots are needed!