There was an FAA legal council brief a few years ago. Commercial flying is considered 135, 121 as 91 sub k. That is the only flying that would count against part 117 duty limits. That being said our FOM says commercial flying and if you were doing 91 helicopter tours and had an incident, you would have to be explaining yo the CPs, DO and VP, why you were conducting commercial flying and have a fresh violation or need to take a Fed check ride etc.