That depends on the client. A lot of clients I have flown actually want that second pilot on board. According to the DO of a company I flew for, the increase in insurance coverage for single pilot pt 135 jet ops was easily the same amount of money as paying the salary for a first officer. So there may not be that much of a cost saving operating single pilot. I think the single pilot operation was geared more toward owner/operators of those jets certified for that.