I only savescum when i feel the fail is really significant or its a relationship check. The rest i let the dice roll how they may and roleplay it
Yeah i'm pretty sure there's a cash prize at the end of that quest too but roleplay wins when Kevin tells that the Shroud did things for justice and not reward 
As for Cait i usually let her rock her infinite ammo double barreled shotgun. I go through ammo like crazy since i don't VATS at all so i like to keep all i find 
I must save scum nearly all the checks just like I must have all the companions even if I wont use them. Also the Shroud Quest is just fun even if that last persuasion check takes nearly all of my save scum luck. 
Your Cait has a gun? All I could find was a bat on mine. Probably just not showing up in the inventory is all. In that case I am taking my combat rifle back from her then. I love VATS, I'm currently trying a sniper build so it helps a lot when the things I'm trying to kill are getting way too close. 