Do any of you guys know if nema 17 (69 oz) will be strong enough to handle cutting aluminum with a 2 hp router (8 pounds)
It will not! Your feed rate and depth would have to be so slow that you might never finish :). The 2 hp router is plenty for the job, but you run the risk of jamming up the bit with metal due to the slow feed rate. When cutting aluminum, it is just as important to be “fast enough”, as it is not to go too fast.