The Mosfet current limiter is likely to be less expensive than trying to use 3 X LM350 as current limiters both circuits can be controlled with a PWM control easily. There is another consideration that should be looked at and that is the sense resistor. For a Bi-polar sensor like the 2N5088 the resistor needs to develop .6 volts drop across it to begin current limiting and the LM350 requires 1.25V which is going to double the required power dissipation of the sense resistors. On the surface the LM350 is an attractive device as it becomes a 2 part limiter but with the discrete's (BUZ71 & 2N5088) there is one additional part and a sense resistor of 1/2 the value and thus 1/2 the required dissipation. Both can be PWM controlled by bringing the sense feedback point to ground. The sense feedback is either the gate of the mosfet or the Adj terminal of the voltage regulator.. For sense resistors I would use metal clad resistors that can be mounted to the heat-sink for good thermal management.
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