[superchink]

This is no longer the case, as of Homebrew 1.0.

See this change: https://github.com/Homebrew/brew/pull/896

[vsl]

This is only about /usr/local itself, not the directories under it, the one with executables - that's still owned by you, not root. Some difference in ease of initial installation, zero difference in terms of (in)security.