I do use a jet wash and always have without issue. What I did differently was this: My last VFR which was a 2014 turned to shit riding it through the winter but the front cylinder head was especially bad (I did paint it when it was off last), so on this wash I bent down with the jet wash pointing up under the fair on to the cyclinder head. Lesson learned and I won't be doing that again but I will continue to use the jet wash. Some people say yes to jet wash and some say no. I'm in the yes camp!
Your comments were especially helpful. I read the manual but didn't really understand what I was reading but I have a better insight now. Cheers.