Guys, the A-boats will be mantas'. It just means they use the troop transports instead of the missile bombers that the rest of the Tau use in fleet engagements.
The only problem is, each manta carries an INSANE number of troops, and probably would warrant special rules.
How about this.
Manta Transports: Instead of acting as bombers, these gigantic troop transports are filled with stealth, crisis and fire warrior teams trained specifically for boarding enemy vessels. When a squadron of these attack craft attack a target, roll a d6 for each strength, on a 2+ it initiates a boarding action (to be resolved in the end phase). Every Manta transport in the squadron counts as having a boarding value of 2. If a 1 is rolled, the crew of the defending ship manages to storm the manta and kill the crew, permanently making the parent ship lose one launch capacity (think Dark Eldar impaler). Do not halve the launch capacity for the transports for being Tau.
Manta Transports are Resilient.