Worth it depends on what your trying to do with your car. If your looking for a fast 1/4 mile then the JRSC isn't going to yield as much power, if that's what you want. It does have other positive points as far as superchargers go. Personally I don't care that much about straight line fast with my SVTF. It's much more about how this car handles to me.
If you want a 1/4 machine, look elsewhere than the JRSC. Its about the cheapest F/I kit you can buy but also doesnt give the gains the higher end kits will give you. A JRSC+BBK on a zetec engine I believe gives you approx 180whp (dont hold me to that number).