From my experience, you're definitely taking a risk. I tried a similar connection once at GDG and there was a backup at immigration. I was in the Sky Priority line, and even it was backed up. I showed the attendant manning the line my boarding pass with my boarding time, and she simply shrugged her shoulders and told me that nothing could be done. I had to be that guy and ask about 15-20 people to let them cut me in line. All were quite gracious and allowed me to do so, and I was the last one to board.