If you're down to cycle-shaving, surely your for loop spells disaster? That the list is cyclic is not so intrinsic that the optimiser can spot it and the null check in elephant ? elephant != head : (elephant = head) != NULL will have to be performed each time round the loop.

I know what you mean, but once I got my head round the conversation, Simon's description made sense to me: if you want to traverse the circle more often than you want to do anything which involves treating the head=null case specially, then the circular implementation without distinguished elements is conceptually simpler, and gives you the freedom to write extremely optimised assembly later, at any point it's needed, even if in the meantime you only have a simple loop.