Thanks for the comments.
WoH, the footstraps are nearly identically located relative to the finbox, its just distorted in the wide angle photo.
I'm thinking that I'll run the mast foot at 130cm on JP at next session and then try the iSonic with equivalent mast position (ie minimum setting in iSonic, per the last picture).
Effectively, the footstraps locations are further inboard relative to centreline, but same longitudinally, forcing a more central stance over the foil. I'm looking for gentle carving with a small sail, rather than reefing a bigger sail to windward for speed. Will let you know how it goes (and hopefully not smash the nose off the iSonic)

Cheers, Mort