In reply to jolivague:
I'd do it the other way round. If you want to extend it, you could cross from the top of Grinds Brook to Blackden (come right along the top of Grinds a bit before crossing) and then round to Fairbrook, cross to the Downfall then on to descend JL. Note these options include nice deep soggy bogs which will entertain you with 35kg on your back, but if you navigate well through the groughs both crossings of the plateau can be fairly straightforward.
Or from the top of Grinds, go west to the top of Jacobs Ladder then south to Brown Knoll and Rushup Edge, and continue round over Mam Tor as far as you want to.