Sal Newbie Here, A few Quick Questions About the Green Capstone...

Is it worth going for if I'm focusing on high fire rate rather than slower heavy-hitting damage? I'm planning on relying on dual synergy pistols after watching Derch wreck face with one, and I'm starting with a fresh level 30 character. This is UCP Sal, mind you. Also if it is worth it, should I pick that up first before working on the other trees? If it's not worth it, then should I work on either the Blue or Red tree instead?