The Galleon has much more killing power than both the Spire and the Mobula, both of which are classified as Glass cannons for the most part.
So, no, the Mobula doesn't have the most killing power. It might have a lot more of it in the future though.
This is more a matter of if I let you below me. The Mobula has the most vertical mobility. And if I can keep your Med. Carronade down while you approach, which, if I can't with a merc and two Artemis, then I deserve to die.
Peaching, realy easy to do as well, problem with your ship is that when you lose your balloon, you lose any advantage you might have had.
Also I'm not as stupid as to approach anyone from straight on, so hold onto that argument