The up and down looks ok from the top of Ringing Roger but I've never tried it (and certainly won't on race day: balls not supplied).
Several people who are way better runners than me have stated they think the up and down might be up to five minutes slower, so that's good enough for me!
Besides, I love the section from Grindslow along the edge to Ringing Roger. It's a great way to finish a long race.