First of all, I'd not advocate for using a 9368 for a new product. However, since I've had my bus monitor since the '70's, when one could still buy the 9368 from NSC and form Fairchild, I still use the thing.

She sort of thing that interests me as an application for this approach is one where I know my MCU is writing data to a given peripheral and I need to observe what it's writing, or when I need to observe what it's reading from a peripheral, one, perhaps, that it accesses infrequently but at the bus speed.

If I had to build that same function today, I suppose I'd capture it with a PLD accessible to an MCU that would read and display what was captured. The advantage I'd be using is the simple and temporary attachment and minimal setup time.

The point is that, while I can't read values that change at 30 ns per cycle any better than anyone else, I can easily read values that change at a 24-hour period but do so in a 30 ns cycle, provided that the hardware can capture them.