Alright, before I knew about this, I took a group of a bit younger adventurers to the Northern Peaks and I must admit, we fared very well.
Although I did warn each one very seriously IG and OOC about how the risks, they decided to join and the result was surprisngly good.
I believe most were level 16 or around that, some around level 14, with a level 20 along too. With a bit of care and tactics we only lost one death and that was due to an ambush spawn and misobidience of leadership.
So I must suggest that rogues be given leeway on this, they can be of great help up there and really make things more fluid.