retrolefty:
it hurts performance no worst then what we have presently, always blocking, at of course with the cost of the additional buffer.
When there's only 2K of RAM that cost might be too high.
The answer is to allow it to be customized - #define a size before you include the header file.
(Even worse I think is the problem that a 128 byte input buffer is currently allocated even if you only ever send data...)