There are many different types of Soft Starters. You have not provided any information on which one you are using.
In terms of noise and CMV for solid state "pulsing" starters:
Ask the manufacturer. They may require you to use a special cable or an inline reactor.
In terms of failing to start for reduced voltage type starters:
Do a Transient Motor Starting analysis to determine whether or not the motors will come up to speed on Soft Start before going to full line voltage. I don't think a Soft Starter manual will tell you whether or not your motor will fail to get up to speed. Many different motors used under different loads have wildly different accelerating torque requirements and thermal limits.
Or:
1. try to start motor on worst process torque requirements from pump
2. motor starts => pat self on butt and go home
2. motor fails to start => turn up voltage, try again, don't burn up motor
