Sorry grantway, but you can write a very long wish list for trails here (sustainability, fun, flow, weather resistance, suitability for all etc etc) and get no-where near needing to boost your progress as a rider. The Hurtwood are to be thanked and appreciated for engaging with mountain biking and doing what they can to accommodate us – they have no need or desire to encourage the type of riding that you are missing… and as you point out similar scrabbly slopes do exist nearby if you know where to look.
If we all keep up the good work of being responsible and not tearing up the woods (plus slowing to a crawl when we go past walkers, horses and anyone working) then the land owners will continue to look favourably on us. As will folk such as Surrey Hills AONB, who are very much behind people coming to enjoy our open spaces and maybe boost the local economy at the same time.