Heavy corvette vs. multigun corvette… old, old debate right there. EDIT- these are stats from Classic Homeworld, not remastered. Do not take this as definitive evidence until the Remastered stats are available.
HW1 heavy corvette: 250 RU, 1700 HP, speed 520m/s.
Kushan- 28-36 damage per shot x2 guns. Bullet mass 0.01, range 5000, bullet speed 15000. 2.8 refire.
Taiidan- 14-18 damage per shot x4 guns (twin turrets). Bullet mass 0.01, range 5000, bullet speed 15000. 2.8 refire.
HW1 multigun corvette: 225 RU, 1400 HP, speed 695m/s.
Kushan- 6-7 damage per shot x6 guns. Bullet mass 0.01, range 6000, bullet speed 20000. 2.0 refire.
Taiidan- 6-7 damage per shot x6 guns. Bullet mass 0.01 range 6000, bullet speed 20000. 2.0 refire.
The heavy simply dealt way more damage- 56-72 every 2.8 seconds for 200-257 damage over 10 seconds vs. 36-42 every 2 seconds for 180-210 damage over 10 seconds. That’s why the heavy corvette was so much better against other corvettes. Against fighters, the multiguns were usually better because they were faster and their guns fired faster projectiles- they could hit agile targets easier and repeatedly. However, there really wasn’t any enemy the multiguns could defeat that the heavies couldn’t, whereas there were lots of things heavies could do that multiguns couldn’t (for instance, although the slower heavy corvette was more easily tracked and hit by an assault frigate, a group of heavies could more easily destroy a frigate than a group of multiguns). Wise players either went for heavies or mixed forces of heavies and multiguns; pushing multiguns exclusively was not ideal since they were more specialized craft.
I don’t know what adjustments were made for the RNG hit system, but assuming Gearbox stayed true to the design of the two corvettes, the heavy is (and should be) the more powerful of the two, and it will still be in your best interests to keep a good number of them around even after you gain access to multiguns- otherwise your corvette force will be at a disadvantage against anything larger than a fighter.