I used a set of these GP gear on my Gizmo so I could have a little bit wider wheel base than the stock gear.
I also used them for my float plane conversion of my Nextar as well, the float plane needed a cross bar to strenthen the gear sisnce they were so bouncy.

there very light weight to start with so I am not sure if lightening holes are going to be all that much of a benifical.

there also made from soft aluminum and are really flexable, mine have started to splay out a bit and need to be bent back into shape by drilling holes in the gear I really dont know if your going to save all that much weight for the weakening of the LG that you will have done to them, if your going to drill holes in the gear I wouldn't make them all that big