Definitely FS are better than PB oils, except for the cost, but don't expect dramatic performance gain (in power, driveability, emission, and FC) if you use FS oils.

I think it will boil down to cost/benefit analysis for your particular car:

a. new vs old car, under warranty or not.
b. ordinary vs luxury vehicle
c. a lemon vs a reliable car
d. how much longer are you going to keep the car.
e. how many cars do you have.
f. how much money do you have.

but with ceddies1025's case, at 1000kms, I'll go for FS for engine and tranny oils unless the car is a lemon, and that's until I can still afford it.