[JonChesterfield]

u16 etc show up a lot and are unlikely to confuse programmers.

Where it does go to pieces is when two different programs both define u16, use them in header files, and then a third program tries to include both those header files at the same time. The big advantage of <stdint.h> is avoiding that failure mode.

The namespaced library type equivalent is something like libname_u32, at which point it's tempting to write uint32_t instead of the libname:: or libname_ prefix.