Data point
I work with some reasonably savvy people, and the first we hear of about:config was when news of how to up the number of active http connections made the rounds 6-8 weeks ago.
What we all did know about is the Tools > Options... dialog, which provides simple access to a reasonable subset of configuration options (and looks enough like what people are used to from IE that it doesn't scare newcomers that way about:config does).
Splitting things up in that way--hard stuff obscured, and common stuff within access with a friendly wrapper around it--seems quite sensible.
