I don't like Grace enough to use it even if it was not so trendy as it is now. As a mn, it's as much of a filler right now as Marie or Lynn. You can't turn around without falling over Ava Grace, Emma Grace, Ella Grace, Hannah Grace and Sophia Grace.
That said, as a fn it is all right but again, I don't really like it. Your Grace Helen combo is the best of the lot, and Grace Ellen is even nicer.
Grace Pearl is the full name of Laura Ingalls Wilder's littlest sister, FYI. :)