Have about 100 hrs in and have seen no issue with balance. I think having so many different ways to approach the game is a lot of fun. One of my favourite partial playthroughs was as as a warlock with Shadowheart and Astarion as my companions. In that playthrough I swapped out Shadowheart's armour and shield for leather only just for fun and as a way of making her less conspicuous as a Cleric. Obviously I was extremely careful in picking and choosing combat as I was extremely vulnerable to melee combat. Some fights and side quests had to be avoided and I chose an evil path ultimately bringing Goblin hell to the grove. Even with that weak party I was able to defeat the Druids though Astarion fell ( I don't use resurrect scrolls on my playthroughs).
I just love the variety on offer even in Act One.
