even though LW9 will subpatch 5point poly's and beyond, it is always best to work withing the 4point rule to keep you mesh as clean as possible. Working with the 5's and beyond can cause some interesting deformations when it comes to render time
I say plot a course with 4 point poly's and keep to it as best you can and use the 5 pointer's only in extreme circumstances. Just remember that if you wanna use models for a portfolio piece and the employer want's to see the mesh.... a clean 4 point poly mesh will look sweet and uber clean..probably helps the render calculation at some point too .