as a thf you will have no problems doing it all solo. the more people that go the more likely someone will aggro one of the NMs that you pass. the only part that is good with two people is in castle oz where you need to open a door and run like hell to get there before it closes but you are a thf so flee your *** there.
Agirlyman, hide and silent oils. You 'might' need help with Yagudo Crest, just because its hard to run from switch to door in time. But at max 2 people should go, once you get more people its always "@S, @I NOW!!" then aggro, death.