So far, I dont' have the color cast and I have not had a problem with their customer support or Lee's when I have called. The examples I have seen show LEE and Cokin with color cast. I think it will come down to personal preference and what does the job for you. I've owned many filters and they all do the job, but I wanted glass this time around, and went off of my friends reviews and some research on the net.
I am talking about the Firecrest filters not the prostop irnd filters which are predecessor to the Firecrest. So, we should be also be sure of which filter family we are talking about. The prostops from what I have read did have some color cast, but so far my Firecrests have none.