I can't speak for herbs, but it's faster for mining. I leveled 1-60 pre-cata post shatter, and I blew through mining so quick I had ore to spare when leveling JC. Iron in Feralas, Thorium in Un'goro, there's more of it, and it respawns faster, often in the same exact spot over and over.
It's really, really nice for those who like to do their own tradeskills. With the vast wealth of some players, the ability to literally buy the world's supply of copper and whatnot was getting tiring.
I can't speak for any nodes post 60, though, and this is all anecdotal, of course.
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