Take a look at the m6 pics here:
http://www.6post.com/forums/showthread.php?t=647170
If you look at the sakhir orange coupe black interior it looks like it's partial leather and I can see white stitching. But this is a launch car so may have been spec'd differently.
I've found this across the board with the options on the m6, it's really tough to figure out how much merino leather is included in extended leather. On my E92 M3 I get merino leather on the arm rests but it appears that on the m6 its the rougher nappa leather...
Also don't even get me started on weather or not we'll get the updated nav professional with the new UI....