You could possibly use a gas spring to lighten the load.
I use a 600oz (40v 7amp) stepper from homeshopcnc, coupled to a 10mm pitch ballscrew. Gas springs help to stop/slow the descent of the router when there is no power.
10 pounds doesn't sound like much of a challenge. I think my router mounts alone would come close to that!
Check out the range of steppers at homeshopcnc or keling.