I don't the there is any benefit to hiding behind C's shadow.
- Arduino already uses the Byte data type, which is non-standard, but helpful
- Arduino doesn't require pointers, which is certainly not standard, but good.
- C does not have many of the hardware specific statements that Arduino uses.
- Arduino's "Setup" functionality is non-standard, but helpful.
Beyond the code efficiency and compactness gain, if 24 bit, and compacted 1bit data types were in the Arduino library the code that uses it would be much more readable.