Adding Encoders to Stepper Motors

I have a EMCO pcmill 55 that I do alot of maching on up to 50 rc material
I am using pico USC for my Motion board and amt 102 encoders from DigiKey 200 IPM feed 4 axis
it cost me about 400 for the upgrade I rewired the motor with shielded cable (everything is shielded)
this is not a hobby machine for me I use for production
if you are worried about losing steps and is it doing what it should be, spend the money put encoders on it
I converted 3 machines with steppers and added encoders two machines have rotary one has linear it will never run without encoders again