I am very curious to know if the 7S36 is really better adjusted.
But about the SKX, I believe that Seiko will stand for the 7S26, because they always used the simplest caliber on the Divers. Appart from the 62MAS, you can notice that the divers always used the simplest (not to say cheapest) version of the caliber family: the 6105 (it could use a 6119), the 6309 (it could be a 6319), the 7002 (no choice here, because the 7019 or 7015 was discontinnued at the time), and now the 7S26.
Don't know the reason. Maybe they will say that the simplest are more robust, but I'm not sure... a 6119 doesn't look less robust that any other 61xx.
Those things are hard to say.
Regards,
Adriano