my xeon mac pro is 6 years old and it has it.
i can't imagine running that much ram without ecc. you would kernel panic or spontaneously reboot constantly. not to mention silently corrupt half your work...
I'm actually rather amazed that at least error /detecting/ ram isn't more common.
no, there are a wide range of memory conditions in which a kernel calls panic, and memory doesn't just flip single bits when it errors out, although that's certainly possible.
It is not flip errors per say that causes kernel panics (it is not going to cause any problems if a section of unallocated memory has a bit flip), but the probability of an uncorrected bit flip in a critical memory location. I am certainly willing to be corrected, but if don’t see how increasing the amount of non-critical memory increases the chance of a kernel panic.