Have you looked at the Hitech ones? their 85mm filters are the same size as the cokin p filters, and are similar priced too.
I have the soft edge ND grads and like them. I find there isn't the same noticable colour cast as I had with my old cokin A series ND grad and ND. Apparently there is a colour cast if you stack them though, but I haven't stacked them yet, so can't comment.