Shooting vs. melee when fighting boarding parties

Shooters always fire at a random enemy. In 2 vs. 1, there's no difference, because there's only one enemy. In 3 vs. 2, or other situations, the shooter is supposed to distribute damage evenly by shooting randomly, but because of how random numbers work, one of the targets will end up with more damage than the other. (Random is not the same as evenly-distributed or nice.) This makes the other combat(s) in the room suddenly become much more lopsided after somebody dies.

The obvious difference is, of course, that only the melee fighter takes damage, so it would make sense to put the healthiest crew member (usually a rock man) into melee. With a little micro, you can swap out the melee fighter when he gets low. Other than that, there is no indication that there is a difference except graphics.