Oh yes I too am a bug fan of double jointed bits. Since you are working on softening his mouth I would recommend a plain smooth french link (or something similar) and make sure you aren't using something too fat (uncomfortable in a small mouth, can't close) or too think (too severe). In the Arab Forum in the English Pleasure forum in the Training a Show Horse Thread there great advice on softening a horse's mouth. I highly recommend the books. Oh and I would love to see pictures of your pony too
. Do you plan on long lining any?