Is it true that a merc leveled from a low level is stronger than one purchased at the same level?

No difference, though i think it was in earlier versions. But not anymore.

But a merc hired in normal has better stats than one hired in nm or hell.

http://www.lurkerlounge.com/spirea/Hirelings/Stats.shtml

This post was edited by Taurean on Jan 20 2022 04:31pm

^ this. Let's say you need to hire another merc to replace the one that you have, and the list of mercs are a level or two lower, you may need to remake game and check the vendor list again. Or, you'll just need to hire the best one and it'll quickly level in time. And, ...