It will, as Mojo says, widen the scale. Whether that's good or bad or bad but workable for you, I can't say. Opening the throat will give it a broader sound, but IME not necessarily darker (although "dark" is a vague enough term Keith and I may be talking about the same thing). If you want a warmer top end, you want the baffle altered, not the throat. A wide open throat will typically give you more brilliance at the top end, not less. Some combination of baffle, tip rail, and curve should give you what you want without altering the scale, assuming you like the essential character of the piece.