The jackets are a nice lightweight fleece. Not too heavy or warm. You can return anything you buy during registration. Exchanges can be difficult though, because they do not always have other sizes available.
We always get the full pin bundle (like to put them on the medals) because we have had issues with pins, usually the challenge, being gone by the time we get to the expo. Went for the runners bundle this time too, since we usually will get the hat if it looks neat, and were planning on a tumbler.