So in my books I have a couple of boardings. Some of my previous questions make that clear. So I was wondering... 
Is it better to: 

- A: use the available railgun tech to kill easier and just plug the ship up if you want to keep it. The railguns are assault rifles with 2kps muzzle velocity. Assuming these higher quality weapons used by the marines can punch through the lower quality armor and ships of the opposition. Why not have my marines fight in vacuum armor and breach the hull as much as they want. 

- B: Preserve the ships on both sides by using less penetration but less lethal weapons. Not to be confused with less than lethal weapons these guns would definitely be lethal but would have a lower chance of getting through the armor. Better for if they board you. 

So the question is which makes more sense? And if one is better why is the other worse?