It's going to be hard to speak to owners about whether they like the HOA since it's a new townhome community. You said it scares the shit out of you not being able to control everything. That's a red flag, but you're aware of it. In the worst case, how upset will you be if you have an overzealous HOA member who measures the height of your mailbox? Can you live with that? Can you live within the ordinary rules of most HOA's that don't have an overzealous board member? If the answer is yes, you're probably ok. The green flag you stated is that you currently live in a historic district. In most historic districts, you have to have approval to do certain types of renovations or exterior changes. You will have the same experience in an HOA in that you need to gain approval to do certain things.
What Gil said about the solvency about the HOA is very important. New HOA's can be a crapshoot. Some developers are great, but others will understate the fees because they want to present low HOA fees to new buyers. If possible, see if the developer has developed any other HOA's and see if you can talk to a board member at one of those HOA's. Did the developer fully fund reserves during the initial operating period when the developer had control? Did they have a smooth transition from developer to HOA? Did they have to sue the developer to get what they needed?