Depends how rough you mean. A lot of that section is more grassy (or at least you can easily ride alongside the stony bits). Obviously I was doing it the other way so am just trying to remember - I think the climb up onto the Downs after Alfriston is a bit rough, after that it's not bad - definitely better than the bits after Worthing. The last 10k or so might be a bit rough, but you could always detour off diagonally to Worthing if it gets bad.
Depends how rough you mean. A lot of that section is more grassy (or at least you can easily ride alongside the stony bits). Obviously I was doing it the other way so am just trying to remember - I think the climb up onto the Downs after Alfriston is a bit rough, after that it's not bad - definitely better than the bits after Worthing. The last 10k or so might be a bit rough, but you could always detour off diagonally to Worthing if it gets bad.