We had a 40 minute layover on our last trip (we booked it before I really thought about how little time that is in "airport time") and I was VERY nervous about it. It was in Nashville, a MUCH smaller airport than the airports in the cities you're talking about.
When our plane landed on our first leg, we just sat there after taxiing toward the terminal. We asked our flight attendant and she told us that the plane that was supposed to have vacated our assigned gate was still there because they were waiting for a couple of passengers connecting from a delayed flight. Eventually they assigned us a different gate and we ended up in the gate right next to our connecting flight. Even with that, we barely made our connection and we had to negotiate so that I could sit next to my daughter. (The other person in that row was very kind and he moved also, which allowed my husband to sit with us, even though we never asked him to consider doing this.)
We lucked out and it worked out okay in the end, but the anxiety that I experienced sitting on the tarmac at the end of our first leg was simply not worth it. I told myself that I would never commit to a layover of less than 60 minutes ever again, and more likely, that number is probably 90 minutes. I doubly don't recommend short layovers if you don't have your seats assigned ahead of time. (We were on Southwest and knowing how the open boarding goes there, I knew the longer we were delayed, the less chance there was that we would be able to sit together.)
I should note that we were flying recently and there were a lot of snow-related delays and cancellations that factored into our situation. However, there can be flight delays at any time of year and in any weather, so it could still cause problems for people trying to make a short layover.
The anxiety and tension just wasn't worth it for me. If I had guaranteed seat assignments, you MIGHT be able to talk me into a 45 minute layover. Maybe. (But I doubt it.) If I wasn't traveling with a child and wouldn't be too stressed out about whether I would be able to sit next to my flight companion(s), that might factor into my decision to accept a shorter layover, too.
Good luck, I hope you find a good flight combo and everything works out for you.
