In reply to GridNorth:
whether someone is capable or not of climbing a grade indoor or out of an equivilent grade is irrelevant as to whether the grade is correct.
a 7a indoors will be the same difficulty for a well rounded climber as a 7a on limestone, or grit, or granite or a slab or an overhang.
its not the grade that changes, it is your personal weaknesses and/ or stengths.
a grade is a grade is a grade. otherwise, what in the world is the point in having them?!
if you can lead steep indoor 7a but know you suck on outdoor slabs, then of course you wont get up a 7a slab outdoors. that doesnt mean its hard, or not 7a. just means you cant climb it. someone that is more practiced at both discliplines will be able to climb both.
subjectivities like the 'scary factor' dont come into sport grades, they are graded for the easiest way up, taking into consideration the entire route, assuming they are safe, because they should be.
Edit- This is assuming the routes are grading correctly, of course.
Post edited at 11:34