I think that using quotes suppresses regular expression processing in split, though.)

Nope:

$ perl -wle'print for split "b+", "abbc"'
a
c
[download]

Which is why you should always use // (or m:: or whatever). Without that habit, it's easier to say things like split "." (which devours all input except newlines :) or split "?" (which dies, since that's not a valid regex) by accident.

Though, as I said, split ' ' is an exception.