I would say if Blu chomps on his bit, that the Happy Mouth bit would be out. It could make dents and stuff on the bit and that could cause him pain.
The other bit looks like a nice bit. That would be good if he likes to play or chomp on his bit.
I'm not sure if you're interested, but I got Vega a Myler bit. It has 3 pieces so it doesn't have the nutcracker action and she really does like it. It also has some sort of metal that makes the horse salivate and help them soften to the bit. They are a little pricey, but I feel it was really work it. They also have different level bits, but I just went by what I thought Vega should have (i got her a low port eggbutt) Myler does have a copper roller full cheek. http://www.doversaddlery.com/product...B%2D01399&qs=1
I didn't buy Vega's bit from Dover Saddlery. I forget where, but it was like $10 cheaper. I'll go through some things and see if I can find out where I got it from, if you're interested