TWI / I2C schematic and code all online now.
If the I2C connection remains open, it works well (and really fast). There is a bit of a problem if the I2C is closed and reopened. Investigating that bit. However, if this is the only I2C device that you are using then no need to close the data stream.
The I2C flow between my keyboard/serial interface to it (also on the same page) works perfectly and is as fast as the other options when converting 115200 baud serial to the display.
Only two connections between the serial/kb and the display are now needed (8 and 4 bit interfaces are still available as options)
http://searle.hostei.com/grant/MonitorKeyboard/index.html
Regards.
Grant