Hi there been shooting the show inserts for the last few years, probably a bit late this answer.
We use a whole range of grads, varying from .6 through to 1.2 hard edge grads, bit are now trying to tone down the look a bit prefering soft edges.All grads are neutral but due to manufacturing proceses there is always colour variation.Formatt are blueish, tiffen are a warmer brown tint etc.. but this changes depending on batches.
There is also a heavy vignette applied at the on line stage.
Cheer Casper