Bridgeport servo motors

There has to be a difference between a new servo motor at $800+ and a
brand (not surplus) treadmill motor at $100+.
I have servo motors that I paid, what some would say "dearly" for,
from a dealer on e-bay. He has sold hundreds of these surplus motors
and has excellent feedback. He states that as many as half have been
used sucessfully on Bridgeport retrofits. Of course, he has an
interest in selling motors so....

Here are the motor specs:

Torque constant: 44oz-in/amp
Voltage constant: 32.5v/1000 rmp
Peak torque: 600 oz-in, or 37.5 in-lb
Nominal voltage: 40vdc
Maximum voltage: 60vdc
Demagnitization current: >20amps
Terminal resistance 2.60 ohm
Max rpm at 50vdc is about 1200 rpm
No-load current <.51 amp
armature inertia .09oz-in-sec^2
4 bolt holes in face for easy mounting.

They came with 1000 CPR Renco encoders pre-mounted. I may move
the encoder to the leadscrew though. The seller states that
these are the largest servo's that a Gecko will drive. The motor
also has a heavy duty front ball bearing. At $150 per motor with
encoder installed, I find them to be quite reasonably priced
considering they are "real" servo motors.

The big question, If I decide to use these motors, is what my
reduction ration will be. I need to trade off between torque and
speed, and the BIG unknown is what torque is REALLY needed to
drive my Bridgeport. I would rather err with a higher reduction
ratio than find myself without enough torque.
If I go with a 3:1 ratio and triple my torque I will get 80 inch per
minute rapids. More than an inch per second SEEMS plenty for me. Why
do people need such fast rapids on a mill? What do you think about
even a 4:1 reduction? Will I regret it later? Do I ask too many
questions? I mostly mill small parts, say 6" on each side or less.

A fellow CNC'er here used these same motors on a Rong Fu mill in
direct drive and said they worked, but were at their limit. My 3:1
reduction will triple the torque, and after all, the only forces
different between my Bridgeport and the Rong Fu is the dead load
of the larger table. (The Rong Fu leadscrew is also finer at .1" per
revolution). The cutting forces should be identical.
The BIG question is will I produce enough power with these motors
to drive my Bridgeport. What do you think?

Scott