RE: Dies that don't use lube
Generally only available for straight walled pistol cases. And not all. Like for a 45-70 or my new 460 smith, not available due to slight taper. Also, I load for a 357sig cartrdige. Its a bottlenecked 9mm basically. But there was one company that made them for that. But RCBS and Lee didn't. thats the reason I say "generally".
Carbide is much, much harder than steel. Thats the reason no lube needed, the case does not embed itself in the metal like steel. I am not exactly sure why they can't make carbide FL rifle dies, but I think it mostly has to do with expense or trying to mill and polish to be able to FL size. The carbide in pistol dies is generally only at the opening.
I don't really see a downside.