In reality both Wings and Dennis are correct.....it all depends how the V-tail is configured to be used. If there is differential movement then the V-tail works as a "ruddervator" which will behave like Wing's aerobird. Now if there is symetrical or opposite differential control then the V-tail behaves as "elevons".
Ruddervators are more mild in behavior and more responsive at slow airspeeds. Therefore thats why its used in this type of aircraft. Elevons would loose roll effectiveness at slow airspeeds, not a good idea for a trainer.

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