That is probably the most annoying post I have read in a long time. Seriously... 6 cycles? The key makes a noise when I press it? Give me a break. I'm really showing restraint by not saying all the things I want to. No wonder apple products cost so much when you have clowns like this purchasing their products.
I'm with this guy.
The problems you described here are very small and un-problematic in the long term. It's your own fault you got one with a duff display.
When my old Macbook Pro broke (several issues with the LCD looking like a mosaic, they replaced everything about 5 times, then switched), Apple replaced it with a Unibody Macbook Pro for free. I couldn't be more thankful. I got it, it had a screen patched with dead pixels. I traveled 2 hours to get an exchange (no genius bar near me had appointments), and the manager went through 4 units with me, all of which had problems. However, they were problems like big chunks taken out of the body of the laptop and the manager was embarrassed. She sat with me until we found a perfect one. However, this was the manager and not me. It seems to me that you've shot yourself in the foot by going back and fore about a 'clicky' enter key. Now you have to deal with what you have got. Too bad. You should have counted your lucky stars when they replaced it the first time.