Ball powders do meter well, but in some measures they can leak. They also can cling to the sides of the powder measure. I've done tests (need to post a thread sometime about it) where I've found that loads with hard-to-meter powders actually have lower SDs when thrown from a measure than weighed individually. I know it sounds backwards, and it was against my original theory, but it's true. Single base extruded powders are cleaner than any double base ball or flake powders, and many (like Hodgdon's line) are much less temperature sensitive. More benchrest competitions have been won with extruded powders so I sure wouldn't exclude them if accuracy was paramount.
Unclenick: From what I've read in Hodgdon's reloading guide Universal is a single base extruded powder cut super short and only resembles a flake powder. Super clean for sure. It's not leaving my bench anytime soon.