Fritz, of the Way of Saimhann, among many others, uses the Terminator-sized base, which is basically the smaller clear flying base which I know Jetbikes used to be packaged with. Now, however, they are packaged with the larger size clear base. I know - I bought 10 not three months ago.
I didn't take my Council to BOLSCON last year for fear they were incorrectly mounted (I, too, used the Terminator bases) and would be disqualified. I've since remounted the unit.
From a test-game with my buddy Bruce... who kicked my butt pretty good. He fed the Council tough nuts and took out the rest of the army around me. Incidentally, I think he's considering becoming a contributor to this blog.
Let's be honest, the Council plays differently depending on the size of the base; there are good and bad features of both.
Before you discount the question entirely, think about it this way: would you be okay with Destroyers mounted on smaller bases? Would you think this was 'correct' even if you were cool with it?
On the other hand, Marine bikes mounted on Dreadnought based would seem downright strange, but it's not really correct to mount them on Terminator bases (though I've seen it done).
I'm not trying to be a dick, nor am I suggesting a ton of people need to rebase existing armies, but if this is a real issue and not just mental masturbation I want to know about it.