I like the Hammerheads because of the results and they are relatively cheap. They fly like field-points, because they are no different. I am using two light rubberbands that come with the package. I've tested and they perform just fine. No premature openings. I also have some better rubberbands(same that my kids used on their braces) I use and it just takes one of them. When using a O-ring, I never use more than one . . .two is too many and could prevent the blades from opening as wabi experienced. Not saying that's the reason his didn't open, but, he did have two on there.
There are a lot of very good choices. If you have a high speed bow, then try the larger cut blades. Why not.