Is it beneficial in any way to have Marines board via dropship rather than from the carrier itself? I can't imagine ever boarding a ship that was still moving nor could I imagine doing it while combat was still going on. Probably more straightforward to just have all the Marines in one troop bay.
It is beneficial if you want the marines to actually survive boarding action and be able to attempt combat against the enemy crew. The boarding action mechanic is something like troop survival chance = boarding ship speed / target ship speed, so assuming your boarding craft are faster than the ship they are deployed from, there is a potential advantage to using boarding craft instead of your larger slower carrier.
If you never board a ship that's still moving, though, the carrier will be fast enough to get 100% safe landings.
That is true. But boring. Boarding whilst dodging incoming flak and beams is much more entertaining. In my opinion. Especially if friendly ships are providing cover fire.
