I have to chime in on this, as the last time this topic came up I was waiting for my X and was chuckling over the comments being made.
Since then, I've got my X, and the few times I've driven while raining, I understand what people are saying. There is a definite "tin" sound of raindrops hitting some part of the roof that I've never had before with other cars. I have an Odyssey, which has a very large roof, so the comment that the roof is bigger is silly.
Now, a few things...I've been driving with a Thule 1600 cargo box since right after I took delivery, so most of my roof is NOT being hit by the rain. The tin sound I hear also comes from right at the front of the roof, and I thought it was only because that's about all that shows with the cargo box on top. Based on what a few others have said here, I wonder if they have built the very front of the roof (the portion that angles down to meet the windshield) out of something different than the rest of the roof. That would make sense given the sound only comes from the front of the roof (for me) and also this is something new...no other vehicle I've ever had makes this "tin" sound with rain drops hitting the roof. I'm not complaining, it's not horrible, but it does exist.