Steve at promaxx (fuckin Steve's everywhere) said he's measured and weighed them and doesn't see enough difference in his opinion. Another topic that half say they won't use them the other half say never use steel again
If he has weighed the entire setup without giving thought to what weight moves and what weight doesn't, I would be suspicious of him.
The point to weight reduction on the top half of the spring is that it moves more.
Think of the components:
1) The full weight of the valve moves along with the rocker
2) The full weight of the retainer and keepers move along with the rocker
3) The upper few spring coils move pretty much with the rocker.
4) The middle of the spring moves at some ratio
5) The bottom few coils hardly move at all.
Realistically, the best bang for the buck is a tool steel or titanium retainer.
To spend a fair amount more, get a beehive or conical. This pays off because those upper few springs are working all the time and the upper coils on the beehive/conical springs have a smaller radius and weigh less.
Now comes the bonus! Because the upper coil on the springs is so much smaller, the retainer is much smaller and there's even more weigh savings exactly where it matters.
