Just kidding? You compared "something" to "something else."
At the very least, a definite plus is that the Winged Serpent will have 12 speed, which means that in an early encounter on neutral ground with enemy angels, it won't have a guaranteed first turn. And the extra 15% defense on the 20th level of the Tazar is just +6 to the defense parameter. And scouting is a sufficient bonus to compensate for that (IMHO, of course).
Все в ней нулево и кукольно.