IMO, and prone to argument I realise, filters are just a means of putting cheap glass/plastic in front of expensive glass to reduce the quality of the image
To get an ND Grad spot on requires the use of a tripod - yes? If so, why not simply bracket - filterless - and sort any too-bright sky out afterwards?
Mountains on either side of lakes are often v-shaped, ND Grads filters are not:shake:; coasts often have cliffs on one side and level seas on the other, ND Grad filters don't account for this:shake:, so in both cases you're darkening part of the image where you don't want to:shake::shake:, meaning you still need some post pro to bring that back - so why not take 2 in the first place?
I've also seen many images
(to be fair, lots of mine in the Cokin-P days) where the 'line' of separation isn't in the right place or not entirely level when using a Grad filter - you can't accurately judge that in-camera, and if it is wrong, your image is stuffed:bonk: - so taking 2 and sorting it out later is 'safer'
Most here will know this, but you don't even have to take 2 images most of the time; one of our contributors here (and a fellow club member of mine) is a master of taking 1 raw image and processing it as 2 to almost HDR it - negating the need for filters in all but extreme cases (in which case, guess what, he'll take 2 or 3)
So what about Polarisers then?

No use with very wide wide-angles, which I use most of the time - so I have only 1 filter, a 77mm Pola, which I also don't use now:bang:
To sum up - I don't like filters much
