For practical purposes, however, a good code profiler would be a lot better. And it wouldn't require source code mods or AOP.
When optimizing applications, it's not as important to know how long each method takes to execute as how long the code as a whole takes to execute for the given task and what parts of the code are offending.
Customer surveys are for companies who didn't pay proper attention to begin with.
subject: AOP with JSf to profiling methods in application