[JKnight]

The need for a locating device can cut into your savings in terms of weight and $$ vs. going with a link setup (particularly if you go the Watt's link route), but the weight savings will still be significant.

I don't think they're the top option available for our cars, but they're a viable one given your goals and restrictions. I'm just a guy with a keyboard who used them on my car though. There is plenty of evidence that people like Mary are using steel springs on their cars (Hotchkis, Global West, DSE) and having success, so you can have good performance without going composite.