Money,money,money
IO540 I agree with you on the technical issues but this is about the Money, at long last we have GPS aproaches in the UK and now that we have the foot in the door with the CAA WAAS can't be far away, this will give us CAT 1 GPS approaches.
With all this hi-tech kit that is unlikely to fail the chances of using an NDB or VOR are very low. If this is the case the NDB will be the clear winner on a cost per occasions used basis.