freeride sail best size for Atom

[bzh56]

Hi,
I have just bought an Atom (wood) as I was very curious about the concept. I am normally into slalom and after a knee injury, I have decided to shift from speed at all costs to comfort, freedom on water, freeride...It seemed that the Atom was an original option. My smaller sail for this board is a Goya Freesurf 6.2 and I am looking at a light wind freeride sail - Mauisail Pursuit. With my profile (88kg, 180cm and good windsurfing experience), which size would you best recommend between 7 and 7.5? I will use the board with straps. I am tempted to go 7.5 and I would like to check with you first and get your feedback. Also I have not tried to Atom yet so how much wind would I need with a 7 or a 7.5 in order to get to planning?
Thanks in advance for your feedback.
Cheers,
Emilio