Just remember, if you go to corporate, the airline favorite line of "its not my job" never applies. There are lots of unsavory things you'll need to do, probably because no one else will do it, or no one else will do a good enough job. If you go 135, there won't be a locked door between you and your pax, so if you fly someone that is a royal PITA, you have to deal with them directly. There is no flight attendant or gate agent to pass them off to.
Personally I can't imagine doing retail 135 post 65, especially after retiring from a major, but to each their own....