Hi, I had my Santorini Black ceramic coated when new and even though I jet wash, snow foam, jet wash, two buckets, lamb wool mitt, drying cloths I still ended up with a few light marks and scratches from washing over the years.
Black seems to show all the marks when the sun hits it so I've just had a minor correction done and had ceramic coating reapplied at 4yrs 3months.
https://www.ftypeforums.co.uk/viewtopic.php?f=17&t=2034&start=30#p57186
Personal choice but for what is an expensive car and a great looking car then I would say it is worth it especially if your keeping it for a long time (or forever for me) to keep it looking its best.
I did consider PPF but the 400 has the body kit so sills and wheel archs are still chip free after 31000 miles. Yes there a few marks/chips on the crab bumper but detailer got most of them out with a touch up pen and bonnet is chip free whether by luck or design.