I can't comment on the balance of the troll race in particular on SoD from personal experience (not having played one...nor any char. to high level here yet)...
But, I did play an Iksar tank to a relatively high level on Live. And, the +1 regen every tick was definitely not worth the inability to wear plate armor there. (As a result, many choose troll... or ogre for the melee stun immunity there. I didn't because I liked playing the Iksar as a race at that time.)
Comparison of Iksar and Troll on SoD:
All same> Infravision, Regeneration, - to skill learning, - to xp
Iksar benefit> Natural armor, fear resistance, forage
Troll benefit> Slam, - to fear and stun durations
Troll (Iksar too?...I can't login at present) penalty> - fire resist
Commentary:
Iksar: All tanks want race changes due to the Natural Armor of Iksar, but the fear resistance is pointless in high-end game (lack of fearing mobs as well as unresistable fear). Forage allows you to feed yourself.
Troll: Slam pointless to all tanks but duel wielding warriors, and even then it is negligible. (Kick vs. Slam <Bash>) Negative to fear and stun durations potentially usable, but not a "major advantage." (Note: All large races gain this.) Negative to fire resist harder to overcome. Large race = difficulty in dungeon environments (without shrink).
I would have to agree that the troll needs "something" to overcome this balance when compared to its major competitor, the iksar.
But, there are many races / classes like this if you are a min/max'er. (Casters could easily do the same comparison.)
In the end, play what you want to play is my opinion.