I've worked in IT professionally since the mid-1980s. My current practice is to write whichever of e.g. KB or KiB that I mean at the time, with KB meaning 10^3$10^3$ and KiB meaning 2^10$2^{10}$. If I'm talking about the RAM in a machine I'll write e.g. "64MiB" and if I'm talking about the as-manufactured and as-marketed size of a disk drive I'll write "1TB." I am not, however, prepared to use words like "mebibyte" in conversation. Maybe one day I'll change my verbal abbreviations from e.g. "meg" to "meb" but I'm not there yet.