Actually, the Vette spring is easy to change because it doesn't require removing the shocks. However, on racing cars shocks are typically much easier to remove.
However, on racing cars coil springs created a bending/binding force on the shocks which results in extra friction. Hyperco markets a line of racing spring perches to address this problem.
http://www.hypercoils.com/Products/Hype ... Perch.aspx
http://www.hypercoils.com/DOC/Centraliz ... d-Axis.doc
This binding issue is insignificant to street cars but is a problem for racecars like the C6-R. The leaf spring is not co-axial to the shock and does not cause this problem. However, the availability of many racing springs (effectively universal springs to fit largely standard racing shocks) makes the use of custom leaves somewhat less desirable.
As for working as an anti-roll bar, please see the link I included in my first post. Effectively, pushing up on the end of the spring (wheel compresses) causes the center of the spring to move down. That in turn reduces the downward force on the opposite wheel. The effect is strong enough that GM was considering not installing anti-roll bars on the 1984 Corvette (again see the article).
I suspect that article is copied from an old book called "The Newest Corvette" by Michael Lamm.
The Corvette is actually filled with examples of GM bucking conventional wisdom and doing innovative things. They seem primitive on the surface but they are often brilliant when you examine the details.
Examples:
Pushrod motor: Clearly this is in part to save money by using a motor that will be part of the same family as the truck motors (but not the same motor). However, the pushrod motor allows a lot of displacement to fit in under a very low hood. It's power density is very good. The standard motor has more power/lb than Honda's 2L used in the S2000 for example. The 7L Z06 motor weighs less than BMW's V10, yet has more power (though only slightly). The enormous torque of the motor allows a fuel saving 1:0.5 final gear. The result is great highway mileage when you want to use top gear.
Balsa Wood Flood: This makes the Vette one of the few cars that uses wood for anything other than cosmetics. It's actually used as part of a sandwich panel in the floor. Much like the honeycomb portion of a honeycomb panel the wood is used to stiffen two thin sheets of metal. The balsa is light, not too expensive and does the job well.
The Leaf Spring: The transverse spring is used front and rear. Compared to the same system with coils, the Vette suspension is lighter and has a lower CG. Additionally, on the C5 Vette GM actually started off with the intent to use coils (they cost less) but they were able to get better shock placement without the added diameter of a coil around the damper.
Lots of unconventional thinking that yields something very good. The same sort of clever thinking that allows a rear engined, air cooled, car with struts up front to be one of the all time great driver's cars.
