The only phase ship that I would use heavy blasters on is Doom, and only because it can brawl with enemies distracted by mines.
Heavy blaster lacks burst on Harbinger. Mining blaster is better but still not that great. Antimatter blasters is probably the best alpha Harbinger can do, closely followed by phase lances.
All of the medium energy weapons stink at anti-shield, even pulse laser (1.1 efficiency, and less DPS means enemy has more time to fire and add more hard flux to your shields, offsetting blasters' worse efficiency) Worse, pulse laser is not good for hit-and-run due to windup and low-powered individual shots. At least blasters are good anti-armor. Pulse lasers are mediocre against everything.
Two blaster Aurora, or one with two pulse lasers and one heavy blaster, either needs to load up on missiles (probably Sabots), or leave too many mounts empty and focus hard on maximum flux stats and shield efficiency. (Missile loadout will probably get the job done faster.) Otherwise, it will stalemate (and lose PPT stall war first) against other cruisers, which is bad when Aurora costs more than most of them.
An Aurora with SO and no vents comes out to 1600 flux dissipation. 2 HB's firing continuously produce 1440 flux per second. Aurora has excess flux dissipation for such a setup and can thus sustain an infinite number of volleys before adding additional vents or guns, so your initial estimate is a bit off.
Even non-SO Aurora can comfortably use two heavy blasters provided that every other mount (aside from minor PD) is empty so that it has enough OP to afford all of the caps, vents, and necessary hullmods. The result is an Aurora with two blasters and mostly empty mounts. Unconventional and looks dumb, but it can duel and win against other cruisers.
Odyssey with two plasma cannons and little else is the capital version of the above.