I decided to get over my paranoia and here I am with a dead machine
What if I ask them to move this screen into the iMac I had at first? That was otherwise perfect. Should not take them longer than 15 minutes to do that!
If they've still got that machine in the store that's actually a great idea and I assure you it IS no more than a 15 minute job for them.
When I sent my 24" iMac in for gradient issues they just replaced the LCD panel itself. It took them a few minutes to do it and then it was on its way back to me. Unfortunately for me, I'm not geographically close to an Apple Store so I have to send mine in to the service center in Tokyo every time. I'm told here in Japan they don't do such work in the stores anyway and even if I did bring the machine in they'd send it from there to the service center.
Best of luck, Fiddler.