Stepper motor or servos?

Do I gather from the threads of discussion that the servo option has some advantages and is becoming more affordable than it has been when compared with the stepper as an option for ballscrew drives? What are those advantages?
Is there a web page for the "Pac Sci" steppers?
Also from the discussion I am gathering that steppers if chosen for my wood/plasic/sheetmetal router probably need to be 300oz or larger in duty.
Comments please
Raynor J.