I was playing on a mostly water map yesterday, and decided to go naval focused. Once i got to the Adv. naval, my remaining opponent had turtled up inland on one of the two 'continents'. So i decided to give the Stingray (the Adv. missile boat) a try, and WHOO BOY! Stingrays are crazy! From what i experienced, it appears they out-range both harpoons, and the adv. artillery piece, they have a pretty fast fire rate for such a long-range unit, and fire tac missiles, so they're super accurate. But WOW that damage! there was not a single building in the enemy base that i saw that DIDN'T get 1-shot by those missiles, not the adv. power gens, not the Adv. mex's, none of the turrets, or harpoons or artillery, nothing. I was able to completely flatten the entire base while sitting off shore with about 4 stingrays plus T1 boat blobs to defend them. If we're eventually getting a tac defence turret or something, then i think they can remain as is, and be a crazy powerful artillery boat. If, however, we're not getting any tac defence, then we might have to look at those crazy huge damage numbers per missile.
Keeping the damage really high would encourage scouting, but I don't think the game makes scouting easy enough right now (especially with chronocam still very much in beta). There's still a lot of balancing that needs to happen, it's true.
They are basically the unnerved catapult. But then naval units haven't seen much love in a long time so them having some silly stats is to be expected. (Scouting not easy enough? Just build a t3 radar [that orbital one] and you never even have to build a scout again... )