Can't hurt to drop the lower units and have a look at the exhaust as part of a survey. It will cost a little bit. For what it's worth, I have 2 2005 F225's and just had my exhaust done as preventative maintenance at 860 hours. They showed no corrosion at all. It's hard to get a good read on how many of these motors were affected. Not a small number, but certainly not all either.