Hi, Dave,
Anytime you are grinding any spring you need water handy to cool it before it overheats. But the "rolling" does work. I do use Wolff springs, but to be honest, I don't quite trust them, as I have had too many of their coil springs that would not hold up and flat springs that either wouldn't hold tension or were so brittle they broke. I have also had Wolff springs for specific applications that were just plain too weak to work properly. At times they seem to be aiming exclusively for the DIY "trigger job" market where some folks consider a super light pull more important than reliability.
The fact is that makers of quality guns build in some "overkill" to deal with adverse conditions (like dirt, mud, cold) and most of the traditional "slicking up" involves removing part of that over-design. But it can also remove that extra margin of reliability; hopefully, the owner will not need it.
I admit that I have not been in the business for several years, and maybe Wolff is better now, but I prefer OEM parts (including springs) if at all possible. As to WWII mag springs, I have found them superior to current springs in most cases (and bad ones are obvious). I don't know why, maybe it is just some more of the corner cutting so common today. Or maybe the spring makers figure that if they make springs that don't last they will sell more springs, something the WWII makers would not have thought of.
Jim