I'm fairly new to this game. Loving the learning. So from a relatively novice perspective I can say that what appeals to me about a Carrera is its simple beauty. As I think Jeff pointed out in his Hodinkee interview, the original Carrera kind of defined beauty in a chronometer..."perfect design of a chronograph" i think was the wording. That is still what appeals to me about them. There are a number of Tachy's floating around for sale right now and they don't seem to move/sell the way the 2447S/N's do... And at least from my perspective, any of the Tachy's, while super cool, do in some way detract from that essential aesthetic. The market would seem to feel the same way.
To the larger question as to whether Carrera's are overrated, it seems more fitting to say that Carreras seem to be touching an approachable-design aesthetic that is capturing imaginations in the watch world right now. My late-to-the-game, new to middle-age, appreciation of watches places me squarely in this group so I do get why they're wanted. I'm frustrated by the pricing especially since I'd love to have a few pieces that explore this arena but that's not where we are right now.
Hopefully that's somewhat on point...I guess we'll see