Chopteeth, the game isn't that hard that we have to make sure the chars are perfect and you can resepc as you learn the game mechanics more. What do I think about your group... We'll you're not min-maxing and your making a team you want to play and it will work! If you want something hard, then you will need to mod, then these decisions become a lot more relevant. I'm playing an all-around group, dabbles in a lot of schools, as Items allow you to do that as well. And I pick and choose what I need as a I go and play with it. One rule I put down, is almost all skills... only one character can use it, so each feels different vs 4 that are equals exploiting and the game has been moderate in difficulty.
My one suggestion though is this and it is too late... only play one-hero per run. To me it gets a bit messy with taking them all. Give them their own solo voice.