In a certain application the case was
1) asynchronus data
2) response required based on received data within a short time and required input processeing for each byte received to keep up.
3) some processing steps in processing of received data take more than one one byte time.

Solution (T2 was not used)
UART int at high priority
T2 int at low priority

The UART ISR recieve the byte, save it, set TF2 and return.
The timer 2 ISR process the data.

This, in effect, created a 'task' with a higher priority than the main.

Erik