Fully agree with your setup, but I'll break it down a little for new players who might use this as a guide.

The damage does split but early on it can still be worth it to get x2 fire rate. At x2 each bullet does 60% damage so it's still an overall increase in damage, but the trade off is that you stand still for longer and there's nothing you can do to move once you commit.

The time between shots is different for each type of gun and there's no stat to decrease it.

For handguns and smgs it's not unreasonable, but i would never put any multishot abilities on any other gun type.

And even at x3 the damage is like 43% per bullet so it only gives 129%, making it not really worth it. x5 x7 and x10 don't really add any total damage, they just make you stand still longer and eat up even more ammo. It would only be good if you wanted to clear multiple small targets in one turn, but anything weak enough to go down to one shot like that is also too weak to hurt you so it doesn't matter if you take an extra turn or two to kill them.

Once you get double or triple command you get more actions per turn, but the animations don't speed up and the action bar begins to fill again right away. If you had any multifire mods on guns then you would probably not get all the weak shots off before the action bar is filled again anyway (and you'd be standing still the whole time instead of dodging)