Yeah, take out the storm bolters, useless. I also think seraphim, you don't have enough anti-tank. Someone just has to take a land raider and you'll be in trouble. The exorcist can only kill so much. With D6 shots, they really are hit and miss. Get 6, great, get 1, your game has already gone downhill my friend.
I'd also swap the plasma pistol on your cannoness for an inferno, for some tank busting action without the threat of death. Also, in the celestian squad, go hvy flamer instead of flamer. It is an assault weapon and would be handier overall when using divine guidance.