I have some concern with balance too.
i just finshed the game yesterday, with a full party composed of Eder, Aloth, durance, Hiravias, Pallegina and my main character : a rogue. the least i can say is that the difficulty is not linear. I had some really hard time in the raedrics hold and the destroyed chapel (did it with my rogue and aloth only) in the beginning. i first found it almost to hard for "hard mode". after thoses early fights, the game suddenly became more and more easy as we gain levels pretty fast.
in the middle of the act II, i had to restrain myself to use certain spells and objects to continue to ejoy the fights.
among those, there are the figurines... summoning wood beetles, adra beetles, black widows and shadows is ridiculously overpowered. i understand their use for a solo player, but with a full party its way too mutch. cast them in the beginning of a fight, take you ranged weapons, and get you some popcorns
spells... i have a few in mind, the best exemple is the bouncing fireball, level 5 druid spell. i can end most of the fights in this game by casting this spell once or twice. with scion of fire, i usually deal 6X150 damage, more with crits, this is wayyyyyyyy too mutch IMO. KO fighter habilities and level 5 call to slumber are too powerfull too IMO. that poor feather dragon spend 3/4 of the fight sleeping on his back. he died at my first attemps, with no tactics, no loss, no placement or anything else, it was my first dragon encounter and i just wanted to see how it comes before making a plan to kill it. to me, powerfull creatures should have immunity to that kind of spells.
hope it can help for an upcoming patch or addon
great great game by the way, loved it.