In most situations, I definitely concur. There are a few cases where I've had to process >10g flat files and I whipped up a specialized tool in C that could run through it nearly as fast as the disk could feed it.
Sure, but I doubt you'd seriously try to handle that with pipes and Unix anyway. 10g warrants someone who knows what they're doing and knows, like you, when the overhead of writing in C pays for itself in faster processing.
Unless you're in scientific community, where it's common to have to convert GBs of data from one weird format to another, or possibly analyzing them, nevertheless knowing only e.g. R and Matlab.