thanks kya (and thanks others too) as you make a point i had not considered, i assumed the later battles would be too hard if i had not max-XP'd the whole time. If I max level prior to the end of the game then maybe the XP grind is not as important as I thought.
In my experience, if you explore the environment and do not skip side quests, you will be ahead of your challengers without unnecessary killing. In acts 2 and 3, fights can easily become too easy on Tactician level, if you are serious about adventuring and if you mind what you are doing. Even as a pacifist.