As a side note, since you mention color, is this material naturally light tight? Or do you paint them in order to obtain the light tight nature? How well will the paint adhere over an extended period if this is what you are doing?
I agree that tube processing does have some nice attributes. The thing that I like is that I can process a number of sheets of film at the same time. I got even development with brush development but my efforts were for one sheet at a time.