On the playthrough I am doing right now, Lone Wolf is an extremely valuable talent.
1 Rogue (lone wolf), 1 Ranger, Madora
No magic on anybody

Madora 7 Con = 294 hp (with 3/5 Picture of Health)
Ranger 6 Con = 210 hp
Rogue 8 Con = 582 hp (443 hp with 6 Con)

Clearly the Rogue is easily the tankiest character. Madora and the Ranger have both died a lot. It's starting to turn around, now that I have more options, but I have frequently been left with only my Lone Wolf Rogue left alive, deciding whether to flee, resurrect, or reload. Combining Madora and my Ranger into a single, tankier person could well be worthwhile. I can definitely say that my LW Rogue is the immovable rock of my group.

When you give up summons, elemental shields, and reliable healing, the huge HP boost from Lone Wolf is definitely a major boon.