The machine posted in my first link, is supplied with A 300W spindle. That doesn't sound very powerful to me. My main useage would be thin plate alu. Do you think it would cope?
it looks like a reasonably chubby motor so i would have thought the torque would be quite good but i guess there is no real way of saying without knowing more about it/ how its wound

iv an outrunner that looks a similar diameter and will happily cut 0.5mm depth in alli 3000rpm 3mm single flute, the power supply is 350w but im pretty sure its drawing nowhere near that

edit: the one you show in the link will only run as low as 5000rpm not perfect but i would have thought doable with small tooling :)