>>717340664
I feel like they're both pretty balanced. At first i thought that the additional storage from having multiple people (and the fact that many utility items can help multiple people, along with rope not being useless) would help, but you're much faster solo and have an abundance of ressources.
We've just failed at difficulty 6, mostly because we were too slow and people were afraid of using the items they found...

Doing it solo was actually way more forgiving. Aside from Medkit/Remedy/lantern/Breadbox allowing you to take quite some damage, you can usually still grab hold while falling to break your fall even without stamina.