Soft start slows the controllers response to the throttle stick command. It's like expo on the throttle. On a geared set up, this can allow your gears to live longer. I started to use the hard start on outrunners, and then liked it so much, I tried it on my geared set ups too.

the CC is quite a bit more expensive, unless you find a real good deal online. To me, the E-Flite ESC isn't an option again.

I'm now experimenting with the Jeti ESC, and have high hopes.