I have a degree in chemistry, and I guess I've always liked mixing things together to see what will happen. The reason for my extensive "collection" of papers is - unreliable supply. For many years I bought what I could get hold of in packets large enough to see me through the next job with some hope of consistency. There was always a few sheets left... Since then I've just stayed in the habit, partly due to fond memories of a very few cases where negative and paper have "meshed" to produce a perfect print in the first attempt. I want to see that happen again!
Ansco 130 continues to surprise me. I can now detect the first signs of "tiring", but it still works perfectly with Ilford MG. Fortezo is a different matter - contrast is definitely going.