I have a small chinese router that uses small end Nema23 motors.
I do a lot of aluminum. I keep the rpms high say 20000+, depth of cut about 0.15mm or 0.005" with a feed rate of about 1000mm/min
with a 1/8 carbide two flute endmill.
I get decent finishes, takes a while but its a hobby so I do it to enjoy it.
I have no problem letting my machine run 6 or 12 hours at a time....
Never any problems.