Nah, the CSB is useless as I have Cid's USB to provide secondary DPS so Zach chain is still better in pretty much all situations. It's not Sephiroth numbers, but he still does decent enough.
That said, the VII 350 Dreams fight has been completed full mastery. Team was:
Zack - Lifesiphon/Ripping Blast - CSB/LMR
Tyro - Dispel/Multi Break - Godwall/LMR
Aerith - Hastega/Curada - USB2/LMR
Cloud - Lifesiphon/Raging Quadstrike - AASB/USB1/Glint/DC LMR
Cid - Cyclone Bolt/Aerial Dive - USB
Managed it in 29 seconds, 3 dead. Aerith couldn't quite get another USB off in time but damage certainly wasn't an issue. Cloud was hitting for 25-30k a hit even through his Mighty Guard.