Having been through IFF as a stud, it was a lot easier to respect the dudes who left the CAF to be IFF IP's vs. listening to the FAIP in UPT telling me what I needed to do to perform well in my fighter squadron.
However, while I think it was good to be exposed to the flying, I'm not sure why it is necessary. It's not like we got good at BFM and Basic SA because we only got 4 OB rides, 4 DB rides, and 4 Basic SA rides, 2 HB rides and 2 SAT rides (for Viper/Strike guys), not enough to become proficient at anything. Also, most of the IP's brief you in the BFM sorties the limitations of the -38 and how you won't necessarily fight the same in your follow on fighters. Plus, the only people I have seen struggle with IFF were guys who did not do well in UPT (ironically guard guys from fighter units) and just couldn't fly good formation.
I think the biggest learning in IFF has nothing to do with the jet. There is a significant difference in the squadron attitude, how it operates, and what they expect of you vs. UPT.