I don't regret getting the car because the car is otherwise awesome (I MIGHT wish I had the wider tires that come with the Sport, but I wanted my light diamond stitched interior). That said, the issue is extremely frustrating and if it turns out to be a huge PITA to actually get it recognized and fixed, I might change my tune.
I've finally made an appointment with the dealer to get it looked at, as I feel like I've done everything I can in my limited capacity including trying to scrape the headliner goo out, stuffing foam padding up there, felt pieces between panels, etc. I can get it so it doesn't make the noise when I push on the problem spot in the headliner, but it always manages to come back after driving the car for a couple of minutes, presumably from the chassis flexing or what have you. For what its worth, stuffing part of a T shirt tightly up in the headliner actually does REDUCE the noise (I believe because it decreases the flexing in the headliner) but I haven't managed to banish it for good.
Unfortunately, I have a trip to Maine planned in a couple of weeks, and the dealer said I couldn't take a loaner car out of state (should have just not asked and done it in the first place but didn't want to bring a loaner back with 1000 extra miles on it), so my appointment to take it in isn't til the 8/19. Until then, I'm still going to try like mad to make it stop.