If I get a 6th generation Apple will get a call for me. My 1st G one had sentimental value (gift from my mother) and was working, I only wanted the battery replaced. AND I have a 6th generation on which I don't like. The click wheel allowed you in the road or in a store without looking to pause and start a conversation, with the 6th G you need to hit the power button to activate the screen, look onto the screen and hit pause. Very inconvenient.
Two things:
Surely you didn't expect Apple to give you back the exact same unit, considering it's a device with a non-replaceable battery? Why do you think they made it so clear that custom engravings will be lost?
Second, just sell your new 6th gen and buy a 1st gen. Pocket the $40 in profit. Heck, you could probably buy two 1st gen nanos for the value of your new replacement 6th gen.