Some solvents react to the brass. I wouldn't get too worried out it as chances are you are going to be using a phosphor bronze brush which will react with the solvents. I use the carbon fiber rods but guess what the brush and jags screw into...a brass base on the end of the fiber rod. Depending on what cleaning solution you use, it may be a non issue from the get go
Some folks say stuff can get embedded on rods, with brass being softer supposedly its more prone to this happening. I've never seen/experienced it, but I am also meticulous on keeping that stuff clean.
The biggest thing is you want to make sure the rod isn't going to be scraping along the barrel, especially the crown. This is where guards/guides come in handy.