I've built the senior and am now building the giant. Do the bolt on wing mod and you will for sure need to do something with the gear. I put a bomb bay in mine and the landing gear repeatdly bent. Get a a good 3/16's aluminum gear. I've put 3lbs in my Senior and it didn't seem to notice it much with a OS61 for power. My kit built suffered the broken wing and stab problem mentioned in several topics. I think if you are using it as a lift you might consider adding support for the wings and beefing up the stab. Mine folded when pulling out of a sharp dive. The kit built plane has no struts, next time I'd add them.

BTW, the Giant has a bomb bay of 18 X 6 X 6 with room for the servos above the bomb bay area.
Thanks, Jerry