Bellfast jumps in with both feet for sure. FAA says you can get lots of ratings with low times. Seaplane add on is five hours if you have a private. Try and get someone to let you use there C206 with only 5 hours on floats. Not going to happen. Commercial Helicopter add on... Not many hours either if you have fixed wing time. Still no reason to jump in a Helicopter and play sky god.,
Licenses themselves are a permit to go learn more. IF you have an opportunity to get more ratings, go for it. It will do nothing more than keep your head in the books a little longer and cannot hurt your advancement in your career.