Yes this "tool" of monitoring a port pin is a regular one that I also use.

I use it in a differnt way though - an LED is connected to that port and used to tell me if my code has branched off to a particular segment as expected. Or if an interrupt ( more than 0.1 Secs )is firing as expected.

Your idea, to physically see the timing using the port pin is a good one. But I guess one must be blessed with a DSO to do that ? The 100Mhz, dual trace that I normally use may not be useful here.

Raghu