I obtained an interesting note from Forecast International, itself claiming to be the "Leading Provider of Aerospace, Defense, Electronics and Power Systems Intelligence. Here it is:
This is one interesting, although not completely surprising development.
During last years Paris Air Show CFM claimed to be even better on fuel burn than the GTF, after adding a 7th stage in the Low Pressure Turbine (the GTF has three) and enlarging the fan to 78".
Now John Leahy says that the LEAP-1A will still be 1.5% worse than the GTF.
Of course, John Leahy also tries to dismiss the B737MAX with this statement - but I do not think he could make the statement if it was not true as CFM (and with them GE and GECAS) are both too good customers as well as suppliers to not tell the truth.
See Scott Hamilton's latest blog entry about the LEAP optimization and the discussion about it here.
There are still a lot of questions about how the LEAP-1B looks like and how it will be integrated into the aircraft. Although GE tried to make a big boohay about finishing the integration studies (this is normally jus a regular milestone and not something you make a PR about...).