Yes, intermixing paint systems is taboo (RM base and Dupont clear), we are not chemists and a lot of money goes down the toilet with experimentation. It may look good at first but if the materials don't chemically bond you're in for a rude suprise down the road. If what you are refering to with mixing systems involves a complete respray (RM originally and a respray with dupont years later) there are no issues, if the car is prepped properly and sealed, topcoating with non oem materials is fine. The OEM does not use the same type of paint we use anyway, RM,Dupont etc.
All paint manufacturers struggle with transparent colours depending on the toners used in any given mix, and to judge a company on a material used 10 years ago can be a mistake as paint tech changes daily. I know people that swear by one brand and curse another, alot of the times it user preference and familiarity with the product that determines the outcome, not the product itself. I am deep into this industry and am fortunate enough to see most manufacturers products, and they are all pretty amazing. Sher willy is a brand I did not like in the past, but I gotta tell you the company has really inproved its products in the last 5 years.
Don't get too hung up on oe paint, we can never duplicate what they use anyway. And at the end of the day no one could tell the difference if you use a quality brand applied by an experienced applicator. I stand by that.
