A couple of thoughts/questions about curved spiders:
1. They do eliminate the spikes because they spread the diffraction over the entire image so it is essentially invisable, though still there. Over the surface of a planet, they must also provide a similar "smearing" as normal vanes, though probably smoother. The fact that the sky is uniformly dark is aesthetically pleasing but I am curious about how the image itself is affected.
2. Thin vanes are good from an optical standpoint. From a mechanical standpoint, thin vanes in tension have the capability of being far more stable than thin curved vanes. I have heard that good success can be had with a thin wire support for the secondary, I would imagine that one could use piano wire as thin as 0.006 inches. I wonder how this compares to the curved spider.
These are valid points however, I'd have to say that if anyone had the opportunity to see the differences side by side, the odds would be zero that the dispersal of the diffraction this way, hinders the image in anyway. If I was primarily doing deep sky, I'd probably go with a straight vane because the spikes look pretty on brighter stars, in fact refractor owners are adding spikes to their astrophoto images for that reason by using strings. I can only say the the images of planets are completely unhindered by Grissoms curves and are only enhanced. It's much cleaner looking and the surface detail is incredible! Even the glow around the planet is hardly evident because of the spider in fact if you look at the image with a standard straight vane, there's still a halo around planets as the spike is thicker at the limbs and gets thinner on its way out.
I wish I could gather all you guys over for a star party at Wilson. I guarantee the odds would be 10-0 in favor of the curve no matter what physics appear to say.
Pons has used very thin piano wire and no matter how thin, there's still a spike. You can test it over a refractor and see this for yourself. I understand that these curves sound crazy. My team and I are the most arrogant swines (haha) when it comes to good optics. We wouldn't be using them if we thought otherwise. I hope someday to share it with others. I really don't feel there's any reason to go with thinner wires, Grissoms curves are already excellent and they are plenty rigid. I'd be a perfectionist to a fault if I did anything else.