My understanding has always been that the way to take weight off of the hands was to have more supported by the butt and legs. This is best achieved by moving the rider's center of gravity back towards the butt and legs, which is done by moving the seat back. Of course, you don't want to change the relationship between the hands and butt, so the handlebars have to move back by the same amount.

The issue of how to distribute the weight between the butt and legs is largely a function of how much the legs support, which is determined by how much force is applied to the pedals. i.e. the harder you pedal, the less weight is on the butt.

I'm guessing that someone on youtube has done a video on this??
I should check my Rivendell Readers and see what Grant's reasoning is/was behind his "raise 'dat stem" philosophy. I'm thinking it was more related to general comfort than getting weight off of the hands.

Steve in Peoria

edit: I found the Riv Reader article, and it's mostly about flexibility and issues with the lower back. Not about getting weight off of the hands.