Just would like to add that I too would greatly appreciate the ability to pause or, better yet, switch to turn-based mode on demand. My personal favourite solution would be if the game switched to turn-based mode as soon as enemies are discovered.
I've played the game for a couple of hours and I mostly like what I'm seeing, but I usually have to reload several times after beginning an encounter with a group of enemies until I can get my mercs to do what I want - and this has kept me from returning to the game.