Like you said, I don't think it's explored enough to really say, but after talking to many breeders who breed Spider x Spider with no unusual results, I wouldn't be afraid to try it. I might do it this season. There was someone else on this site also doing some Spider x Spider breedings that I'm interested in seeing the results of. You have a link to "a couple white snakes hatching"? I thought it was only one that started the rumor.
If Pinstripe is co-dom people probably don't breed Pin x Pin too often because you can't tell visually that you've created the Super... Same with spider.