using interrupts in FRC

[Ether]

I'd like continue a discussion that started in another thread. I made a new thread here as a courtesy to the OP of the original thread who expressed his desire not to discuss the larger issues involved.

Here are the things I'd like to have a discussion about. I'd like to hear from FRC programming gurus.

Scenario1:

A team has code which uses 100ms and 20ms periodic tasks, and they are running low on throughput margin (i.e. CPU usage is too high). They think that they can reduce CPU usage by using interrupts instead of periodic tasks. What say you?

Scenario2:

A team has subsystems that need to respond to sensor data changes within 1ms. Should they: a) use Interrupt Service Routines to control these subsystems, or b) carefully investigate other approaches (such as a hardware limit switch directly connect to a motor controller for example).