I don't think there is any doubt that 103 contains hydrocarbons (gas & potentially condensate / oil) but the huge question is it commercially viable?
The % chance attributed to 103 by D&M took into account the close proximity of the local discovery. The fact that they found hydrocarbons is not unexpected in fact I think that it was almost definite that they would find something with the surveys & local neighbourhood.
I think that the 20 odd % (can't remember exactly what it was) chance of success for 103 was more to do with whether the find is sufficiently large & commercially viable. Flow rates & it would appear water saturation are the important thing not merely the presence of hydrocarbons.
So 50:50 or 25:75 or even 75:25 could be just as valid a guess for success for 103.