I see no problem with breeding spider to spider. Since the wobble varies so much from snake to snake, the severity of the wobble is not really genetic. I have a spider male (mild wobble) who's spinner offspring has moderate wobble (he still eats and lives normally. He just gets a bit loopy if he's startled or gets too excited). I also bred a female spider with only a head tilt and her offspring have yet to display a wobble (though I do not doubt they will develop something in their life time).
I have heard of spiders with "no wobble" (all spiders have some degree of a wobble) producing babies with severe wobbles and individuals with moderate to severe wobbles producing spiders with mild wobbles. There really is no way to tell what the severity of the wobble will be. I would say breeding spider to spider is safe and I plan on doing it sometime in the future.