I would say not much improved accuracy, if any at all. The Accustock uses an aluminum bedding block that offers very secure stock to action fit. The action and stock should not change alignment during fire and usually don't with the Accustock.
Now... If the Accustock doesn't fit you well, or you shoot off of bags and could benefit from a flatter forearm, or more weight on the rifle, then a stock change might help.
Another option would be to skim bed the Accustock. This might give you better contact with the lug and accustock aluminum frame.
Bottom line is you never really know unless change the stock and have good pre/post change shots documented so you can see and measure any benefit, but I would think it wouldn't be much. Would probably be better to spend the money on a custom barrel, better recoil lug, etc.