Actually, VFDs are usually a pretty good solution IF you have a need for variable speed. With a VFD you can get full torque without the extreme excess current because you are changing the voltage and frequency together, whereas a soft start changes voltage only.
To explain, lets look at starting Across-the-Line and with a soft starter. If you look at maximum output torque from a 3 phase Design B motor (most common type), that occurs at the point in which you attain the Breakdown Torque (BDT) of the motor and is about 220% FLT, but it needs to be at about 90% speed to attain that. So until that point is reached, the most you can get is Starting Torque, a.k.a. Locked Rotor Torque or LRT, which is about 160% Full Load Torque (FLT). But as Jim Dungar said, that requires you to apply Full Voltage and the starting current jumps to 600% FLA, which may cause a line voltage drop, which then reduces the output torque by the square of the voltage reduction. If you limit the starting current to, say 450% with a soft starter, that equates to about 75% current and therefore 75% voltage. So .75 x .75 = 56% of LRT, which means 160% x .56 = 89.6% of FLT. If you set the soft starter for 350% current limit it nets you about 55% FLT for starting. Hence the term "Soft" Start. That's why you need the "dual ramp" version if you occasionally want more starting torque under some conditions. By the way, yes an Across-the-Line rated bypass contactor would indeed provide MAXIMUM starting torque, but may cause the voltage drop problem described above.
With a VFD, you can attain FLT at almost* any point in the speed range and in doing so, the motor will draw no more than 100% FLA. Better yet, with vector drives you can make the motor put out BDT, so now that means 220% FLT at any speed, yet the current necessary to do so will be only 220% of FLA. So a VFD is actually BETTER at delivering maximum torque to a load at startup with minimal effect on the power system (as far as current draw is concerned anyway). The only big issues are that they can cost 5-8x the cost of a soft starter in larger sizes and if variable speed is not necessary, can also cost you a lot in operating losses. A VFD running at fixed speed is, at BEST, 98% efficient (usually less) and those losses are constant. So 250HP = 186.5kW x 2% = 3.73kW in constant losses, x 8hrs/shift x $0.15/kWh = $4.50/shift in losses, which comes to about $100 month. Still, if your power system is weak, it is sometimes the only choice that makes sense.
*Sensorless Vector drives can deliver FLT at virtually any speed, Closed Loop Vector can deliver at absolutely any speed, even zero speed. Non-vector drives start to lose torque control at speeds under 1/6 rated but can still usually outperform soft starters for starting torque.
