Hi Guy,
I've used both versions of the 200 f2 (although not simultaniously) and both versions of the 300 f2.8 (tested together). With regards to the 300 f2.8, both had nanocoating so only difference was the .5-75 f stop advantage when hand holding. Since I generally don't hand hold a 300 f2.8, the differerences between these two lenses was non existent with and without teleconverters. With regards to the two versions of the 200 f2, I don't recall if the older VRI lens had nano coating or not, but don't think it did. I didn't run across flair problems with either version but in specific circumstances, the differences in coating may make a slight difference. Other than that there is the slight increase in efficiency with VR in the newer version and I could sort of see the slight difference when using this lens hand held. Small as it was, it could be detected but if I found a great buy in a VRI version, I would grab it. Other than these two differences, not much real world shooting differences to speak of in 95 percent of situations, except for possible slight reduction of flair shooting towards bright light. I didn't test for flair specifically with either lens.
Best of luck with your "research"...remember it's just research. Keep repeating this phrase whenever the thought crosses your mind to purchase..."Its Just Research". Now repeat after me.... LOL!
Dave (D&A)