I like to play my games leisurely, and was exploring. Intend to do the tutorial dungeon. Does get a bit boring, though. Everytime, I decide to try a new build - do the tutorial with it.
You are right. I only got till around level 3 with DOS1 before putting it aside. However, I did it a few times, including the last time in Hard mode.
Is Tactician mode harder than the classic edition's hard mode?
Even in hard mode, getting to level 3 is nothing. Level 3 is still the starter area, things don't start getting hard until quite a bit later.
Tactician is a LOT harder than the vanilla hard mode, so if you're saying that you never got past level 3 with any character, then you will have a hard time with Tactician. Play Explorer or Classic first and finish the game. That will give you enough understanding to be able to handle Tactical a lot better.