> It launches more server tasks when the load goes up, shuts them down when the load decreases
In my experience, this isn't a good feature. It sounds nice, but it can often mean everything runs fine while your load is low, but when your load gets high, you spawn more workers and run out of memory. It's much better to have a static number of workers in my experience.
Crash recovery is handy, if needed though.
It's useful if you have multiple FCGI programs that handle different kinds of requests. Depending on what's being requested, programs start up and shut down.