What would be the reason (if any) to run caitken &sh over veteran gunners?

Am i missing something?

Veteran Gunners requires you to reroll all of your dice, including favorable results such as Red Double Hits and Black Hit Crits. C & S permit you to choose any dice of one color, so you can keep the desirable results.

Ah that does make sense. Which one do most players go with?

Because you need to reroll ALL dice in the dice pool, Veteran Gunners is very unpopular. Rebels will probably go with C&S every time if they HAD to choose. But turbolasers like Linked Turbolaser Towers are more popular than C&S. C&S is probably most useful on an Ackbar Assault Frigate.

Veteran Gunners is most useful on an Onager, especially in combination with Gunnery Chief Varnillian.

If you have a ship that has a lot of black dice, then you are better off with Ordnance Experts. This allows you to reroll once for each attack, including anti Squadron black dice.

C&S is good for a red dice throwing ship that can't use leading shots like maybe a torpedo scout mc30 or a Vanguard Neb. I'd only use veteran gunners for the onager if you get a particularly bad roll on the superweapon.