ND grad filters are good to have for landscape, essential really, IF you're not very good at photoshop, or dont wanna spend a lot of time in photoshop in post-production, or you absolutely HAVE to capture the image in one exposure. however, im pretty experienced with photoshop, and i prefer to spend more time behind a screen than behind a camera, because when ur taking pics, ur light is constantly changing. if u spend more time behind a computer, when u HAVE the time, u can take many more comps IN the field. my process is this. i usually leave my filters in my bag, use AEB, and fire off various exposures back to back with the amount of stops i want. sometimes it takes firing 2 AEB sets, but thats ok. this allows me to take many more shots, take many more comps, and combined the elements from various shots that i like. maybe the sky is good in one, but the land sucks. so i grab the land i like from a brighter exposure, and mask em together in PS. 95% of the time i never use filters. filters are cool, but they take more care, more time, and they only offer a straight line, which in most cases is not what your landscape will have, unless its an ocean scape. often times the dark part will darken a mountain u may not want that dark. basically, u can do all the things a filter can do, and much more, using just multiple exposures and photoshop. the ONLY time a ND grad is ABSOLUTELY needed, is when u HAVE to get the shot in 1 exposure to capture movement of something. for that reason i still own a set of soft and hard ND's, 1, 2, and 3, stops of each. good to have, but not necessary at all most of the time if you know photoshop.