To be honest, I have been looking at the pony heads more and more and I think that small blades in multiples will work really well. I am think of making the ones I was sent with 2-4 size 00,0,or 1 blades. I think this will give it more action and might even make some noise as they try to flutter around on each other.
My personal opinion on the right size is one that makes the total length of the swivel and blade come right to the first bend of the hook. I can't say this is right because I have not fished them yet but is my first impression as to what is the right size.
I love taking my kids fishing, now if I could just manage to fish at the same time.