I believe that Promoted posts should ONLY be inserted in the People I Follow feed if it's a post by someone I follow. I would not want posts inserted in there by people I don't follow. The Follow feed is there for a reason. Unless I misunderstand what you wrote, and this what you meant.
I like the idea of posts being inserted into the regular new feed. Can you elaborate on what you mean by slower and faster rate? Will the promoted post be inserted several times, in a repeated fashion, every few hours? Or will appear sooner after they hit the promote button? I'm not sure I understand the function entirely.
When you say Upvote Services do you also mean the free options that are run by humans, or just the bots. I don't personally see a problem with the free human ones. I don't use bots, only tried them twice, and it wasn't worth it for the budget I was willing to spend on them. I do use the free services though who will sometimes upvote me.
How would you implement this, as an upgrade to the Steemit website?
Now, will the promoted posts drown out the non-promoted posts? Will people be resentful towards those who promote. How will they know if someone promoted with a budget of 1 SBD, whom someone might want to encourage and upvote, as opposed to someone who promoted using 50 SBD? How will this help those of us who do not use any paying services?
Thanks :)