I've been reading the latest post by Mike about a new feature of non-rated registration, and upon reaching the following sentence a horrible realisation struck me down.

During the round, you will not be able to see whether another participant is registered as rated or non-rated.

This essentially makes predicting the rating delta during the contest an impossible task. Even now the predictions are not accurate, but this change, I imagine, will render them utterly useless. The way it looks right now is that Carrot will no longer be useful.

If you're not yet familiar with Carrot, I recommend you try this wonderful extension out while it still works.

Edit: Although, now that I think of it, Carrot's function of evaluating the rating your performance corresponds to will still be quite handy.