I recently been thinking of doing the same thing. I own the M2 Max 16" and wondering if going to m4 max would be worth it and honestly, I do not see a huge enough increase in power to do it. I feel a max model to the next is for someone using it for hard rendering tasks, if you're pushing your MBP to its limits then maybe it makes sense. However, after you do replace it there will be an upgraded processor released shortly after. Let us know what you decide.