Derek, i would personally suggest that if you were going to use the machine for a router then sticking with ballscrew this way you will increase your torque over belts, the way i did it was to use a 2:1 Ratio to for every turn of the pull on the servo the pulley on the ballscrew turns half a turn. this does have its trade offs i.e its reduces your rapids if you are using steppers but will double your torque. also doing a gearing mechanism will increases your accuracy.

I overdid things but i like to over engineer things. to overcome slow rapids in my system but maintain torque i used servo motors that can spin at 3000rpm, but unlike steppers, servos maintain there level of torque through there full rev range!

Hope that helps a little buddy.