Is anyone using Braid as their main line on a Carolina Rig to a fluorocarbon Leader?

Yes

Some do, I wouldn't.  The dragging over over rocks and the sinker sliding up and and down the line, will wear the braid and snap off a lot of rigs.  I rig a lot, like a lot... and I run 20lb Abrazx or 22lb Sunline Structure Flouro main line to a 12 to 17lb mono leader.  I break off only when I'm really negligent about knots.

Yes I do.  Just check your line alot.  Rocks and shell will add abrasion to the line.  It's not s big issue for me , but I am a line checker.  Maybe not every cast but after every fish and hang up.