Grims are better in matchups where I can't out tempo opponents and I have to grind out my wins. This would apply to most mid range decks like bug, Jund, blade mirrors etc. Grim is a x for 1 while bolt is a 1 for 1. I also feel that 8 1 for 1 removal spells is too many. Bolts went to the board to replace Lavamancer. I'm not sure what else is needed in the board to be honest. Extra bolts would probably be good against elves.