Inevitable, but it seems that spinnaker fabric is finally done as the middle choice of ultralight shelter fabrics. I'd been on a mailing list for Gossamer Gear, probably the last of the big names to sell spinnaker shelters, waiting for news of when the SpinnTwinn would be back in stock, but the news is that the SpinnTwinn is done.
As other manufacturers have found, the inconsistent quality of recently produced spinnaker is the problem. However, apparently the design will return with a new fabric. No idea about their other shelters.
Luckily I picked up a Spinnshelter from the Gear Swap here, so my shelter needs are now covered, but I'm intrigued to see what the new fabric will be.