I tried a few fights on Tactician (my normal mode) and then on Balanced because I had to replay long scenes and wanted to spare me time (mostly to get rid of shiny benefits, like the glowing weapons from the cloister, as I hate visible magical effects), and Balanced is much easier and fights are relaxed. In the fight against the Gith inquisitor for example I had to use all I had on Tactitian and had one dead after the fight, on Balanced I got out of it nearly unscratched. However Tactitian is also quite manageable most of the fights.
If things go wrong, it is mostly a question of initiative. I wiped one time so far in the game (I'm only at start of Act 2), when the Gith captain in the cloister attacked and several adds game in. Two chars were dead at start of second turn, no one face rolls enemies with 2 at 30% hp against 8. Second trial was totally different, 3 of my group went first and the fight was easy. So Mr. Random won/lost the fight.