Having recently played Solasta for the first time, I've got to say their reaction implementation works flawlessy and doesn't interfere with the flow of combat at all in my experience. I truly hope Larian will make some real considerations on how to properly implement reactions. Whether my mage uses his reaction to attack a fleeing monster, or saves it for a potential shield cast later, has a very big impact. This is something that is highly unlikely to be fixable with mods, and needs proper support from the game itself.