I agree with your findings madfloyd.
No matter what the weight of thre Stainless Heavyweight, it will, or never can be the correct weight for every single instance.
You may find 10 in a 100 LPs, that are perfectly flat, no dishing, in which the Heavyweight will work perfectly for both sides of the LP.
But, in many cases, you'll find an LP which is dished, meaning the LP lays Convex on one side, and concave on the other, but without Lip Warps. Then what do you do?
The answer is a Threaded Clamp, in which you can personally adjust just the right amount of clamping force to lessen these anomalies.
For me, it's worth it to let the Platter spin a revolution, or two, to see how the LP reacts to clamping force. I may add a little more, or a little less clamping force to lessen the Cartridge bobbing up, and down like it's on a roller coaster ride. Those hills can be heard, and IMO really detract from good vinyl playback.
Then there's what I call the rare occasional weird Lip Warp, on which nothing short of throwing it in the Furutec disc flattener, or using a Periphery Ring will resolve. Like a few have said, LP's, with such severe warps should be given away, or chucked in the garbage. For the few that one might have. is it worth it, to spend $500 to recitfy? Mark