I agree. All else being equal. A well tuned 420 grain arrow, will knock the water out of a 500 grain corksrew. Weight alone is only part of the equation.
So many variables, and changing one thing change everything. If a shooter is a perfectionist get a saw and build your own, this will allow the most options to really customize the spine and find one your bow really loves in the numbers you want. Other wise find a shop willing to discuss arrows and builds and has knowledge and will attempt to tailor to those needs. Adding weights to the front of arrows, or cutting them short to maximize FOC, spine charts tend to go out the window.