I haven't used Chaff products but do use Spillers Happy Hoof.
From looking @ the other info. they seem to be close to the same thing, just a different company.
I use both the Laminitic for a Cushings pony and the Competitive for our traveling show horses. Its easier to travel with and can be fed in any amount and out of a bucket,less chance of them picking up something from previous stall occupant. Can't say that I've seen any difference except amount fed. Baled hay apprx 1/4-1/2 bale per day. Bagged hay 1 bag per 1 1/2 week. Although it is a UK product most Purina dealers can get it.
Spillers Horse Feeds - Happy Hoof®