Cokin nuances

[Rickjs]

So I'm about to go filter shopping and figured I would probably go with a Cokin p series filter system. I'm seeing that Cokin had the nuances series that are glass. Was wondering if anybody has any experience with them? I have also been looking at the Formatt Hitech pro irnd and firecrest filters. I am leaning more towards the firecrest or cokin mainly because they are glass, and I like glass. Also, I see people on both sides saying that these filters give a color cast, aren't you supposed to adjust your white balance with a grey card to help reduce this?