I haven't tried to achieve equality of spine through cutting, but I’m sure it's possible, because cutting seems to affect spine more than weight change. That is, a 1/4” change in length will have a noticeable effect on spine, and 1/4” is about .008 of the length of the arrow. It takes about 25 grains to have much effect on a 100 grain point, which is a 25% change in weight, by comparison.
I like to keep arrow length the same, for aiming purposes, but I will sometimes change weight if I want to use the same bow for target and hunting. For example, I might use a 75 grain point on a .600 spine arrow for target, and a 175 or 200 grain point on a .500 spine arrow of the same length for hunting.