I noticed with the T500 I purchased there existed some keyboard flex. I got sort of used to it. One of the keys broke (my own doing). I replaced the keyboard from my old T60 (FRU No: 42T3209). Wow! What a huge difference. The old design is superior in every way. It does weigh a little more but the difference in feel and ruggedness make it a much better choice. I am going to order a second 42T3209 keyboard for the T60. If anyone gets annoyed with the keyboard flex, I suggest searching (ebay, parts surplus) for the 42T3209 keyboard. To Lenovo: Please consider the old keyboard design in future models. Thank you.
There is a definite trade-off between the two types of keyboards. The more flexible keyboard is significantly lighter and more spill resistant (assumption). It also may provide a better ventilation due to the holes. The more rigid keyboard is heavier, more solid feeling (no flex), and may be less spill resistant (assumption). It may be a good idea for Lenovo to offer an option when ordering a laptop whereas customer can choose the type of keyboard, listing the benefits of each type.