You seem like in the same boat as myself. I read that while the Reading and Listening scores rarely change, the chances of the Writing or Speaking to increase is more. So just how much difference will a 7 or 7.5 make in your crs score? I think from 6.5 to 7 in Writing adds several points.
My current CRS with LRWS 8.5,9,6.5,8 is 388, if my writing score changes to 7 it will be 445.