The case has struts that are supposed to prevent flex, they actually work pretty well, except near the top row in mine... there was apparently a gap between the PCB and these struts, and what bothered me the most was not the imperceptible flex, but a pretty loud noise when I typed in the top 2 rows of the keyboard. At first I thought one of the keyboard legs was off, it sounded like the noise you get when a keyboard wobbles due to an uneven standing surface. I would hear this thud noise way before the tactile bump of the blues was reached! So I did the foam mod, and even put a thin piece of foam completely over the top strut, which eliminated the noise. I don't really notice any flex. It's a very fun board, I don't regret buying it, although I'm not nearly as productive on it as I am on a Kinesis Advantage. I bought the Poker for the portability, and for practicing QWERTY, since all my Kinesis boards are set to Dvorak.