In my experience (and thats somewhat dependent on the fleet you play), a) Battleships are not supposed to act alone - a lone Battleship might take out two type 1 or two type twos - but rather as the core of a flotilla. That being said, you are constantly forced to decide if you'd rather shoot the battleship or start whittling away the escort.
By sheer toughness by slot, Battleships are more flimsy than smaller ships - but - they have a lot more Structure and they have a lot more slots. Most battleships need to lose an entire arc before they are even mildly threatened - which means that they soak up a lot of fire. If you ignore the Battleship and keep pounding the escorts, you have a harder time breaching them and you will likely be forced to take a brutal beating from the BS batteries.
After having played about 40-50 games by now, I found the battleships initially adequate, then way to flimsy and now I am back to think they are roughly where one would expect them to be. The game clearly revolves around squadron based combat, not engagements of individual ships. Usually it is not your choice what ships you play but rather a scenario both players agree upon before the game.
Like in Battletech, extremely boring min-maxing is possible and the game as far as I have seen it is not balanced towards avoiding every possible route of exploit (or even the majority of them) with regard to force-building. In that regard it is definitely more like Battletech than, say Warhammer. To me that is what I come to like about the game. In contrast to Force-Building types of Wargames, the game mainly (only) takes place AFTER the players meet and while they interact, instead of being mostly decided by the time the armies (fleets) hit the tabletop, pending 2 (to me boring) hours of dice-rolling and mostly executing pre-formulated battle plans.
So, are Battleships point for point an equal power compared to four type 1s? If you choose your type 1 wisely, probably not. Are they durable and fulfill the role of centerpiece in a formation: Yes.
