Hands-On RTOS with Microcontrollers

How much delay is acceptable?

Depending on the exact function being implemented, minimal delay may be desired. In this case, buffer-based implementations can sometimes have a slight advantage. They allow the calling code to be set up as an extremely high priority, without causing significant context switching in the rest of the application. 

With a buffer-based setup, after the last byte of a message is transferred, the task will be notified and immediately run. This is better than having the high-priority task perform byte-wise parsing of the message since it will be interrupting other tasks continually each time a byte is received. In a byte-wise queue-based approach, the task waiting on the queue would need to be set to a very high priority ...