I'm getting ready to make a more significant investment in filters as I'm prepping for the leap into the 8x10 world. To this point, I've been using Cokin P filters yet continuously read that they are far below the quality ladder from Lee / Hitech / etc... I completely understand that when you are talking about grad. ND filters that it is worth the investment to get a premium filter to avoid the color-cast, etc.
My question is, for black/white contrast filters (#25 red; #58 green; etc...) is there a significant quality difference between Cokin filters and the higher-end filters (specifically Hitech)?