Here is my experience FWIW
Monday July 25th I scheduled dealer appt for studdering issue
Facts:
Car has studdered and hesitated since new
Build date 06/04 Legacy GT MT wagon.
18230 studdering miles
ECU sent out for reflash - 3 days turnaround - despite being told initially it would be 8 days.
Findings
Has definately improved situation, nowhere near as bad as before, but still present. Especially in 3rd and 5th gear medium acceleration from 2500rpm.
I'm not sure i could recommend it as a completely worthwhile fix - but if its available, my motto is to take it.
