I use braid ranging from 40to 80 lbs on my baitcasters, and don't have any complaints with casting distance, but I tend to throw heavier baits. Backlashes are pretty much always of my own doing, for sure.
As far as diameter is concerned,I still have a spool of Sufix Performance Fuse 30 lb, on one of my baitcasters. It's almost as thick as the 80 lb Power Pro. Mind you, that line is older by a couple of seasons, and has seen a lot more action, so it's "fuzzier", but a thick line for its rated strength, for sure.