The new troll rewards system is very nice, though the most expensive "Smith" option is rarely useful for armor.
The player can have the Blacksmith smith 3 items for them. They always get to choose from 2 random weapons and a random armor generated using Dwarven Metropolis tier distribution. The items have 15%/55%/20%/5% chance to be upgraded to +0/+1/+2/+3 respectively and are never enchanted or cursed.
At this stage of the game we are usually looking forward to a plate armor, and may have one at +0/+1. Often enough we can upgrade and reforge for 1500 favor and come out with +2/+3 plate.
Now the Smith option, for 2000, has a low chance of producing such an armor and often only produces a Scale mail, rarely a novelty at the troll's level.
Perhaps the armor item should be guaranteed to be a plate?
Okay I thought +0 was also possible. If +2 is common then it is a fair gamble. How many runs arrive to level 13 without a +1 or better scale mail? That is the case where Smith is a likely improvement. I don't have numbers but playing Mage with 3 challenges I usually have such armor by level 14. And usually cannot wear a plate yet...
What is the typical depth where players get to Strength 16?
I'll admit that a run with challenges requires extra work anyway, so there it makes sense to seek 3 plates and backtrack.
+0 is possible if you only smith, but you can combine a smith with an update to get guaranteed +1 and high chance for +2.
I don't have analytics data for STR progression, but I would expect 16 STR to be floor 13 or 14, which is where the 6th strength potion is dropped. Possible floor 16 or 17 if the player misses a potion.