Now TV have published a help guide to the boost. It appears only two Sky Sports channels are 1080/50. Sky Sports Main Event and Sky Sports Premier League. You also get three simultaneous connections,
Fox is staying at 720p and Gold in SD. As I speak, SyFy is still in SD, although that is going FHD.
Presumably most of the content on the channels that show drama is 25p (or 23.976p sped up to 25p) - so those remaining 25p makes sense. Sky News would benefit from 50p, as would any channels carrying entertainment shows shot 50Hz interlaced.
Gold would be nice in 50p when it is showing stuff shot interlaced in studio - such as sit coms.