Actual PR, sticky comments, manually done, do follow attributes, custom comments and auto approve blogs are basic features of blog commenting service. After 4 years we need to move up just as niche relevant blogs, blog relevant informative comments, OBL less than 25 and 1 month replacement of guarantee if any blog remove your comment.
I know it is very time consuming but thats the quality and work a professional buyer looking for. I always know this service also better than Fiverr gig therefore MOD approve you. Hope you keep the quality and take blog commenting service to next step.
BTW best of luck with sales.